Bring Out Your Dead (Disease in Twilight: 2000)

This is another in the series of posts exploring the various "mini-game" mechanics within the Twilight: 2000 v2.2 rule-set, this time the "unseen" threat of diseases - a threat that can't be solved with bullets alone. I suspect diseases are underutilised in most campaigns, possibly because of their threat to player agency and the usual emphasis on combat as conflict resolution.

Like a lot of the game mechanics, the rules for diseases are based on a  complex combination of different dice rolls and sub-systems which can be difficult to appreciate the impact of without working through examples and/or using the rules in extended play.

Plague: Carting the Dead, by J. Moynet (Wikki Commons)

The White Horse: Disease

"The horseman on the white horse was clad in a showy and barbarous attire. [...] While his horse continued galloping, he was bending his bow in order to spread pestilence abroad. At his back swung the brass quiver filled with poisoned arrows, containing the germs of all diseases." 

- Vicente Blasco Ibáñez, "the Four Horsemen of the Apocalypse"

Disease is considered an important "scenario generator" in the game, likely more so than many RPGs - although the nuclear exchange and war inflicted heavy casualties, it was the resultant infrastructure breakdown and outbreaks of disease that dropped the global population to 50% or less in some areas. In the resulting Twilight World, the threat of disease remains ever present and is suggested to drive stories other than just straight "shoot and loot" conflict.

By my calculations, a disease very commonly affects settlements the group may encounter - almost 1 in 4 settlements if using the random crisis recommendation (see comment below).

Disease rules are given on pages 244-245 of the v2.2 corebook, with specific details of the various disease on the following two pages. The whole "mini-game" mechanics for disease are particularly complex, even when compared to other "non-combat" threats such as running out of fuel, vehicle breakdowns, starvation, fatigue, and radiation.

Other than this main section the only references are in the Biology (people/water), Medical: Diagnosis (draft animal/people/water), Survival (water), and Tracking (wild animal) skill descriptions of the difficulty levels for detecting disease.

Medical: Diagnosis (EDU) overall is the most relevant skill, not only because it aids with recognising contamination across animals, people and water but also as it is used to diagnose the correct disease and modifies the recovery roll for the infected character. As Medical is a "cascade" skill, characters with Medical: Trauma Aid or Surgery have some skill with Medical: Diagnosis.

Catching a Disease

There are three ways to contract a disease:

• People encounter (Biology or Medical: Diagnosis check)
• Settlement (includes merchants, army groups; possibly marauders, hunters)
• Encampment (includes refugees, stragglers; possibly marauders, hunters)

• Animal encounter  
• Draft animal (Biology or Medical: Diagnosis)
• Wild animal (Tracking check while on the trail)

• Drinking contaminated water/food (Biology, Medical: Diagnosis  or Survival check)

Note: it's not explicit in the actual Encounter section but the implication is that Disease should be checked for *every* relevant encounter eg Animal, Group, or Settlement. The risk of a particular people or animal encounter (or water) carrying a disease is given on the various tables on page 274 of the corebook.

Disease Frequency and Type Tables 
(Twilight: 2000 v2.2, page 274)

People: contracting a disease is dependent on the sanitary conditions - "settlement" reflects groups that practice good sanitation and so includes merchants, army groups and possibly more organised marauders and hunters. "Encampment" reflects less sanitary conditions and applies also to refugess, stragglers and some marauder / hunter groups. The base chance for "settlement" is 11+ on 2D6 or 8.34% (1 in 12) and for "encampment" is 16.67% (1 in 6).

Note: if using the Settlement Crisis suggestions, any settlement that rolls of "9" (Epidemic, doctor needed) or "10" (Disease, medicine needed) indicates a potential risk of contracting disease above and beyond the tables. So even if there's only about a 10% chance on average of disease for a given settlement/encampment, there's still a 20% chance (1 in 5) that it's been affected by disease in some way, further underlying the frequency of disease as a potential threat. Taken together, this is a 28% chance (roughly 1 in 4) of disease (recent, current or imminent) being an issue for any given settlement.

Animal: the base chance of an animal carrying a disease is 5.56% (1 in 20).

Water: this refers to water away from settlements including rivers, lakes, streams, springs, abandoned wells. The risk is the same as for animals ie. 5.56% (1 in 20). If detected the contaminated water can be avoided or boiled to avoid exposure - this would seem to be sensible and standard practice for any military trained characters with Survival skill.

Detecting Disease

Detecting a disease is an AVG difficult skill check (x2 Attr+Skill), with the skill applicable depending on the encounter as noted above:

• Biology (EDU) is used for animals, people and water
• Medical: Diagnosis (EDU) is used for draft animals, people and water
• Survival (INT) is used for water
• Tracking (INT) is used for wild animals

Medical: Diagnosis (or Biology) is the most useful skill for detection, and although Biology is also used to manufacture antibiotics, Medical (any) has much broader use. Tracking for wild animals seems to refer to identifying a diseased animal before the encounter in order to completely avoid them, I'd consider that once encountered Biology and Medicine: Diagnosis could be used instead.

A character with at least a "Novice" level Asset (Attribute + Skill = 9) in one of the relevant skills above therefore has a 90% chance of identifying a disease, with Experienced or higher level characters with the correct Asset capable of *automatically* detecting disease.

Even an unskilled character with a high EDU or INT Attribute level (8+ for example) has a reasonable rate of success at 40% (difficulty level is doubled from AVG to DIFF as unskilled).

Risk of Infection

Encountering a contaminated individual, animal or water alone is not enough to risk infection depending on how the disease is spread, it depends on whether they are exposed to one of it's modes of transmission (page 245):

The Referee should consult the description of the disease to determine how it is spread and compare this with the group's particular vulnerabilities. A disease spread by tainted food is not spread to those who don't eat the food, and one spread by contact doesn't affect those who do not make contact with the victim. A disease spread through the air places all characters within range at risk. 

As noted above, boiling contaminated water before drinking removes the risk of infeciton, even if the presence of disease is not detected - this applies to dysentery, cholera, hepatitis-A, typhoid fever, and possibly minor waterborne diseases. Only dysentery and typhoid are normally contracted from "wild" water sources however, the other waterborne diseases result from encampments/settlements.

Resisting infection is an AVG Constitution check (2x Attribute) on d20, with the target score modified as follows based on how vulnerable the character is and the disease's virulence:

• -1 for each Fatigue level (includes those from starvation)
• -x depending on the disease's "Infection Number" (up to 6)

For most unfatigued characters with an average CON of 5 for a target of 10 or less, the base risk is therefore 50% ie 50% chance of catching the disease if exposed. As most diseases have an "Infection Number" of at least 3, this reduces the target to 7 and gives the character a 65% (2 in 3) risk of contracting the disease. More virulent diseases (those with Infection Numbers of 5+ like Cholera, Pneumonia and Pneumonic Plague) increase this risk to 75% (3 in 4) for an average character.

Characters with weak base health such as a CON score of 2 or 3, have a high susceptibility to disease as their base chance of avoiding contracting infection is 30% or less, before the modification from the disease's Infection score! 

It's easy to see how Fatigue and starvation can rapidly lead to infection even in normally strong fit characters - as each Fatigue level reduces CON by 1 *and* reduces the Asset by another -1, the risk of infection rapidly escalates and easily spreads in communities or groups of soldiers without food even if they start with good health (reflected by a high CON score of 8+).

Note: the example on page 245 using Monk is wrong, his target should be 12-2-3 or 7 as the AVG difficulty should double his CON of 6 - the worked example uses a base of 5. So if he rolled a 4 on d20 he would have actually avoided contracting the disease. 

Diagnosis & Misdiagnosis

Image: Snook 8 / Deviant Art
(Header for this article on ISIS and Ebola)

Overall, the specifics of the various diseases as presented in dense blocks of text are difficult to understand, so I've collated all the cramped text information into a table to analyze further:

Summary Disease Diagnosis table
(derived from pages 246-247 T2k v2.2 corebook)

Looking at the "Diagnosis" table, food/water contamination seem the most common mode of transmission, whereas typhus, rabies and bubonic plague are more specific and readily avoidable.  Only pneumonia and pneumonic plague are spread through the airborne route.

Pneumonic plague is the most virulent (Infection Score of 6) and the two most difficult to diagnose diseases are hepatitis A and typhoid fever, although the latter cannot be mistaken for a minor disease.

Diagnosis in phase I of the disease is a Medical: Diagnosis check; this is one step easier (FOR becomes DIFF, DIFF becomes AVG, AVG becomes EASY) in phase 2 of the disease. Most diseases can be misdiagnosed as a minor disease leading to ineffective treatment and potential dire results.

Effects, Treatment, and Death or Recovery

This is where it becomes complex. Again I think constructing a table helps for this section.

Each disease has an incubation phase (no effect / unable to diagnose), a phase 1 (harder to diagnose but easier to recover from) and a phase 2 (easy to diagnose but more severe, treatment *half* as effective and harder to recover from). Treatment begun earlier works better, so diagnosing the disease correctly early makes a significant difference.

Recovery rolls are a D10 that must exceed the "base recovery" number.

This is modified by:

• + CON score (average +5, max +10)
• + Medical: Diagnosis of the treating character (effectively up to +5) 
• + bonuses from correct treatment (assumes correct diagnosis, up to +8)
• -1 for inadequate food
• -1 for inadequate shelter 

All the diseases have a "base recovery" number of 18 or more - assuming adequate food and shelter, a character with an average CON of 5 and an average roll of 5 or 6 still needs the benefit of the treating character's Medical: Diagnosis skill (effective max 5) and treatment to have a chance of recovery.

If a character fails a recovery roll during phase 2 they have a risk of actually *dying*. 

If the character does not die they suffer debility (modified by the recovery roll success or failure).

Summary Disease Treatment & Recovery table
(derived from pages 246-247 T2k v2.2 corebook)

Comments on Specific Diseases

Rabies particularly seems quite insidious and lethal - although potentially readily avoided, it has a long incubation period of *weeks* and it's "base recovery" is 26 with a death probability of 100% ie automatic death if recovery fails. Although the 14-day DE vaccine provides a +8 modifier, the D10 + CON roll still has a target of 18, relying heavily on the treating character's Medical: Diagnosis skill. Without the specific treatment (the rare vaccine), an infected character with CON 10 and an excellent roll of 10 on the D10 needs to be treated by a character with a Medical: Diagnosis skill of 8+. The prolonged debility period of 20 weeks is the longest of all the diseases presented.

The two plagues (bubonic and pneumonic) are also essentially lethal on a failed recovery roll with extended debility periods of 15 weeks each. The next most deadly is actually food poisoning, with a death probability of 50% and a difficult recovery roll although if a character survives, their debility period is relatively short at 2 weeks.

The other disease (including minor diseases) are rarely lethal and easier to recover from, with debility periods of 6 weeks or less and easier to source treatment options.

Tuberculosis is a notable omission as it's apparently very common in war scenarios. Although perhaps more insidious and slow, it's very difficult to treat with standard antibiotics and exacerbated by malnutrition and low immunity eg HIV infection.

Summary

Looking at the disease rules closely, I'd consider that disease as threat or potential stimulus for the player group probably deserves more of a show given the conditions of the Twilight World. I've not come across much mention of it in the Polish supplements I've looked through and if anything the conditions in Poland in the Twilight World of 2000 seem setup so that disease should be a common enough challenge encountered.

The detail and complexity of the rules in T2k v2.2 are considerable - 4 rolls to check if a character is infected and up to 5 rolls to check for recovery or death. On the one hand, this is probably one of the more comprehensive treatments in an RPG I've seen but on the other hand, it may be overly complex and present a barrier to its use during play.

Hopefully, the additional tables above help with this however and I think the whole "mini-game" can be summarised into set steps from the dense block of text (see the Appendix below).

Weighing up the probabilities and taking into consideration the resource-poor world, the role of disease in the game seems to be to help drive the player group towards larger towns and cities seeking advanced medical treatment or as a barrier to prevent them exploring in a particular direction.

You might have an APC, enough fuel, parts and food to make it to Bremerhaven and a good chance of dodging former Soviet soldiers if you keep off the roads but if one of you gets sick, say your mechanic, and you don't have the correct medicine that side trip into town may cost you precious time. Or do you make a decision to leave your plague-ridden companion behind...

Appendix: From Contact to Recovery (or Death) 

This is a summary of the "mini-game" of disease for easy reference by a Referee:

Contracting Disease

• On an Animal or Group (people) Encounter check for presence of disease (2D6 roll)
• Check if a character drinks potentially contaminated water (1 in 20 risk)
• Determine the type of disease according to the relevant table (page 274 or above)
• Check to see if the group detects the presence of a disease (Medical: Diagnosis or other)
• Referee to rule to determine if a character is potentially exposed 
• AVG:CON check to see if exposed character contracts the disease 
• Wait for the incubation period to pass and then inform player of symptoms

Overall, this involves four rolls: a 2D6 roll (check for presence), a D10 roll (type of disease) and two D20 rolls (detection check, CON check to avoid disease). Potentially could be simplified into four D20 rolls.

Treating the Disease

• In phase 1, check to see if the disease is diagnosed using Medical: Diagnosis

• IF the correct diagnosis is made, apply modifiers and check for recovery at the end of phase 1
• IF recovery roll is successful, then the character recovers and suffers the debility effects
• IF the roll is unsuccessful, check again at the end of phase 2
• IF the phase 2 recovery roll is successful, move to the debility phase
• IF the phase 2 recovery roll is unsuccessful, check for death
• IF the death check fails, the character dies
• IF the death check succeeds, apply debility 

• IF a misdiagnosis is made, apply any applicable modifiers and check for recovery
• IF recovery roll is successful (unlikely),  then the character recovers and suffers the debility effects
• IF recovery is unsuccessful, recheck diagnosis (half difficulty in phase 2)
• IF correct diagnosis is made, apply correct treatment and check recovery
• IF misdiagnosis still, check for recovery (less likely)
• Otherwise follow the same steps as above until death or debility 

This requires at least two D20 checks (diagnosis and phase 1 recovery rolls) but if the character is misdiagnosed in both phases increases to four D20 checks (two diagnosis checks, two recovery rolls) and a D10 roll (check for death). The D10 death check could be converted into a D20.

Food for Thought (Foraging in Twilight: 2000)

Foraging in the Twilight World?

One of the main thematic limiting factors to overland travel in the Twilight World, other than fuel and vehicle maintenance, is securing a reliable supply of food... or rather the core thematic factor is the risk of lack of food in the wake of the breakdown of structured society.

The core rules, p148-149 imply that as MRE and similar pre-packaged food is in short supply (or runs out quickly), most of this must be sourced from the land, although this can be supplemented by hunting wild animals, raiding village fields in Spring and Summer, and to a lesser extent bartering with the more civilized towns and emerging "free cities" such as the baronial towns of the Margravate of Silesia, Krakow or the recovering suburbs of Warsaw.

In the spirit of my previous posts about stills and maintenance, I'll have a look at this aspect of play, work through a few examples using pregen characters to keep things in context, and see if the rules can be simplified for use of use for a beginning GM starting a new campaign.

For simplicity, I will be assuming any characters are travelling without animals ie not cavalry, as the rules for feeding and upkeep of animals will need consideraton in a separate post.

Mini-games within the larger game can add a lot of depth and provide motivation to move the story in particular directions, but there is the risk of bogging down play with unfamiliar or non-intuitive rules. I'm coming at this from the philosophy that the starvation mini-game within T2k v2.2 should provide opportunities for rewarding play rather than limit them. 

Looking over the rules, lack of food is very, very bad.

Lethal even.

Eating only half-rations (1.5kg wild food per day) results in a persistent Fatigue level (-1 to all Attributes, negative effect on direct fire combat) until a full meal is eaten for each day of half rations (max 10 days) and can actually *kill* a character after several months. However, half rations are a valid short term option for most characters and if they become Fatigued from other reasons this is still manageable if necessary provided they avoid conflict and don't need to make critical skill checks.

Starvation from not eating anything however results in an additional Fatigue level (and resultant -1 to all Attributes and cumulative effect on direct fire combat) every day until all Attributes are at 1, and *kills* a character after a month. Being starved for more than a few days is crippling and makes additional Fatigue very dangerous as the character becomes much more prone to collapsing unconscious.

So as if there wasn't already enough to worry about, avoiding starvation is very important in the Twilight World and thus the Survival skill comes into it's own, with Tracking being of secondary significance for hunting opportunities. However, unlike running out of fuel or vehicle breakdown, lack of food only hinders progress - it doesn't stop the group in it's tracks completely so it's more of a debuff or side-trek trigger than a show-stopper as it were.

The default T2k v2.2 campaign begins on July 20th in Summer, only changing to Fall (Autumn) on September 1st and then Winter begins on 1st December, 2000. These dates become very relevant as the campaign progresses - there's only 4 months until Winter brings with it a real risk of starvation.

Foraging

Foraging for food while travelling overland is the default assumption built into the rules. It's not clear how long wild food keeps for but based on the following examples, the rate of consumption is high enough for this to be somewhat of a moot point in most cases.

For the majority of travel through the Poland of the Twilight World, the characters will be moving through wood, scrub or possibly fields and avoiding swamps meaning that wild food should be readily available. Exactly what constitutes a meadow is a bit unclear to me, so I'm going to keep the assumptions simple and consider meadows to surround villages / towns and to line roads that don't run through either woods or hills. I'd consider hills to be covered in scrub unless clearly forested.

Each character must eat at least 3kg of food every day to remain healthy. - T2k v2.2, p148

For a foraging character, the desired attribute is Intelligence (INT) for the Survival skill. Fortunately Tracking (used for hunting) is also INT based, so an optimised forager build can readily double as a skilled hunter without needing too much investment - more on that further down.

As per the Foraging Table and rules, p148 of the T2k v2.2 corebook, successfully finding food is a Survival: DIFF check so a dedicated foraging Novice/Experienced character (Survival Asset value 10) has a 50% chance of success, whereas an Elite character (Survival Asset value 15) has a 75% chance of success. A character with a minimal Survival Asset (value of 5) has only a 25% chance of successfully finding food each period spent foraging.

An Outstanding Success (exceeding the required roll by 10 or more) doubles the amount of food obtained, but is rare for the majority of characters only relevant in the handful of cases that the forager has an Elite level survival asset when there is a 25% chance of doubling the food foraged - relevant for a single traveller or maybe a small group only in practical terms.

This means that on average a single character with basic Survival Asset of 10 or more living off the land and travelling through Woods or Scrub in these seasons can find enough food to feed themselves reliably by spending a single 4-hour period of easy work foraging each day.

If the same character is foraging in a Meadow however, this drops to on average one third the amount, meaning that if the character only spends one 4-hour period, they can't even reliably find enough to feed themselves on half rations for a week (50% of 2kg per period). If they forage for two periods per day, the can on average only find enough to survive on half rations for the week and suffer the "half-starved" Fatigue penalty.

Once Winter sets in 4 months into the campaign, living off the land becomes impossible through foraging alone, although fishing (see further down) and hunting may be viable options for some characters. The group needs to have secured a food reserve to travel overland or negotiate a reliable supply, which often means remaining stationary and in the vicinity of a large enough town.

Example: Bobbi-Lee, the pregenerated scout has a Survival Asset of 10 (INT 7 + Survival 3). While travelling overland on foot through the Woods or Scrub in Summer or Fall, she can forage a 1km square area each day with a success rate of 50%. On average, she can find food most days and build up a small supply of extra food without difficulty. 

If travelling through Meadows (or swamp), Bobbi-Lee will have a harder time, averaging only enough food for 1 day over a full week period - this means she will quickly start feeling the effect of starvation and will need to carry extra food or change route to spend time foraging in a Wood or Scrub area to build up her supply. Regardless of what terrain she's travelling in, Bobbi-Lee will need to obtain and carry extra food to travel through Winter or resort to either fishing or try her luck with hunting the occasionally encountered wild animal.

Depletion

Foraging Matrix (1km squares)

Unfortunately, foraging is limited by the fact that resources in the 1km square target area deplete rapidly - this is irrelevant for an individual or small group on foot or carrying sufficient stores of fuel that moves to a new location each day, but becomes a factor for slower moving larger groups (3 or more characters) if distilling fuel for vehicles forces them to remain stationary for long periods of a week or more and characters need to be assigned to routine guard duty and preventative maintenance.

The matrix diagram to the right provides a visual aid to picturing foraging depletion - consider each diamond as a 1km square area with the party's camp as the black circle in the centre.

The four central darker green squares are readily accessible by a character without adding additional time, as are the next ring of 12 lighter squares within 1.5km of the camp (about 15-20 minutes walk, still within radio range for the most part). These 16 squares are the area that is quickly depleted within a week (2 foraging periods per day eg one person foraging twice a day or two character foraging one period each).

Foraging with more characters depletes the immediate area faster and foraging only on period a day depletes the area half as fast, but this immediate area only provides enough food in Summer or Autumn on average to feed 4 characters at half-rations for the week.

To supply enough food on average for 4 characters at full rations over the week, another two 4-hour periods must be spent foraging per day and the foragers must ultimately range further afield, The lightest squares shown (the 8 indicated and the 12 corner squares) are a significant distance from camp - characters foraging these squares (because the inner squares are already foraged out and depleted) must spend an extra half 4-hour period traveling out and back and travel out of radio range. Alternatively, a pair of characters working together can forage these outer squares in one 4-hour period, remaining within radio contact of each other at all times.

Example: a group of 4 characters is travelling overland in their modified 5-ton truck, distilling methanol as they travel using their medium still. For every 4-hour period they travel they must spend a week distilling more fuel and so need 12kg of wild food per day for the week for a total of 84kg of wild food. On average, if the foragers have Novice/Experienced level Survival Asset of 10 and spend two 4-hour periods per day foraging in a Wood/Scrub area, they can generate 42kg of wild food between them, just enough for half-rations for the whole group. More skilled foragers increases the average amount of food obtained but not sufficiently to provide full rations reliably.

For larger groups staying stationary longer to distil enough fuel, the options are to subsist on half-rations or send multiple foragers to range further afield - this effectively constitutes a short journey in itself for foragers and triggers a separate chance of an Encounter for the foraging party, including a potential Animal encounter that can be a Hunting opportunity (see below).

For most larger parties, carrying a supply of food when travelling overland is essential as even having half the group out foraging with at least a Survival Asset of 10 for a 4-hour period per day in Wood/Scrub is likely to supply only half-rations on average - even with a higher Survival Asset of the foragers only increases the amount enough to provide a stockpile for extra days at half rations, not the full amount of food.

Fields

Foraging in fields, also known as harvesting (or pillaging if without permission), for a single 4-hour period supplies enough food for a single character for 10 days (Summer) or 17 days (Fall), making the prospect of raiding a local village's crops for food a tempting one, but not one without consequence.

Access to fields isn't a given and should require at least negotiation or barter and can be considered an exception to general overland movement. This provides a potential story opportunity as the villagers are likely to demand some service from the characters in return such as defeating local marauders or helping repair electronic equipment.

Fishing

Looking at the rules, there's almost no point trying to fish without proper equipment as it shifts the task from DIFF to FORM (x0.5 Asset) and crafting fishing equipment (rod, line, nets etc) is only a Survival: DIFF check without any other prerequisites.

Kalisz Area Tactical Map

The limiting factor would seem to be the presence of water, but looking at the tactical map of the area around Kalisz to the right, there seems to be an abundance of small streams and/or ponds and lakes in addition to major rivers such as the Warta, so fishing is a valid option for a Poland campaign.

Fishing however is less efficient on average than foraging in a Woods or scrub area - on average a period spent fishing by a character with a Survival Asset of 10 produces about two thirds as much food (average 3.5 x 50% success = 1.8kg of food per day or 12kg per week). It is however more productive than foraging in a meadow or swamp area and is an option when the area has already been foraged out.

Again, the amount of fish produced is likely to be consumed rapidly, but large quantities will need to either be frozen or chilled (requiring a small refrigerator freezer, powered by a vehicle battery or small generator). Optionally the group may choose to salt, pickle or smoke the fish to preserve it - I'd suggest this is a Survival: AVG check that takes a single 4-hour period in most instances.

Although less productive in Winter than other months, the option of fishing is freely available year round if nearby water and on average more productive than foraging in the Winter and even Spring seasons - in Winter and Spring it should therefore be the preferred means of obtaining wild food when applicable and may make the difference between starvation and survival for a character travelling alone. Relying on fishing limits a group living off the land to travelling in areas where slow moving water sources are readily available.

Grenade Fishing

As evocative as this option is, it's a potentially expensive waste of military resources ($4 each for fragmentation or concussion grenade) but it can produce a useful result if the character lacks a significant Survival Asset. Most starting military characters will have a Survival skill of at least 1, but need an INT attribute of 4+ to have at least a 25% chance of successful fishing (or foraging) so this option may be more relevant for civilian characters caught in the wilderness.

On average, there are 70kg of fish available in a given slow moving body of water (roll 2D6x10kg). A single grenade produces on average 10kg of fish (1D6-1 then x4kg) ie enough food for a single character for 3 days, but there is a 1 in 6 chance that no fish are brought to the surface and a grenade is wasted.

Grenade fishing is therefore very useful as a last resort by unskilled characters whose military resources have become less important than avoiding the effects of starvation. It may also provide a welcome windfall of surplus food for a group crossing a river or travelling near a river as part of their journey but is unsustainable as a primary food supply.

Hunting

Hunting requires Animal encounters (p162-164), which represent only one result in most terrains (10% chance) except for Hills and Woods where they contribute two possible results (20% chance), and Roads and River where they are not an available result. The type of Territory does not significantly affect the results as even in a Devastated Territory (+2 modifier), the result of the 1D10 roll with modifier still includes Animal options. From the rules the Season is also irrelevant, which suggests that it's relative contribution should be higher in Winter when foraging and fishing are much less effective, bartering with villagers is more difficult and harvesting from fields is not an option,

There's not a lot of clarification on the rules for hunting, other than it uses the INT Tracking skill. Even the description of the Tracking skill on page 138 is unhelpful:

Follow in snow, loose soil, or sand: Average. Follow across rock: Formidable. Detect disease in animal from carcass: Difficult. Determine time since quarry passed through: Formidable. Determine number of animals or people in party: Formidable. Night increases all tasks by two levels of difficulty. 

As there is only one encounter option per 4-hour period of travel or once per day when not moving, there's only a base 19% chance of at least one Animal encounter per day if moving only a single period, increasing to 27% if travelling for two periods (8 hours). This increases to 36% and 48% if the character is in Woods or Hills however, but drops to 0% if travelling along a Road or River. For a group stationary while distilling fuel, small hunting groups can travel up to 10 miles from camp easily in a single 4-hour period however to increase their chances of encountering prey for one hunting party, but this strategy also provokes the risk of other encounters that may need to then be dealt with by the smaller group.

Successful hunting is seemingly more determined by encounter ranges, available weaponry and stealth/combat skills than a Skill check - there's no option to "Hunt" like there is to "Forage" detailed unfortunately, so RAW Tracking only has application if the prey flees or for tracking human groups and vehicles. Perhaps a Tracking: FORM check could be used to locate the tracks of a potential Animal encounter in Hills or Woods (increased to Impossible for Clear and Swamp terrain, not applicable for Road or River terrain) and then the Tracking skill used to catch up to the Group?

Despite the difficulties, use of resources and even risk of injury, the potential yield in food (30% of animal weight) is considerable - most of the large animals will produce >30kg of wild food from just a single animal, sufficient to feed a single character for more than a week if stored and preserved appropriately - smoked, salted or cured being common options although if the group have available refrigeration and freezer facilities this is an alternative (see under Foraging above).

So hunting is a low frequency, high risk but significant payoff food supply option and becomes relevant for larger slow moving groups where foraging enough food becomes difficult if the group remains stationary for long periods and depletes the local resources eg. while distilling fuel for their vehicles.

Barter 

Technically, barter isn't an overland travel option, but it is relevant when considering a reasonable overland journey to secure extra food for use in an emergency or to enable a trip in Winter when living off the land becomes impossible, or at best difficult if travelling along a waterway.

Bartering is an option that has to be pre-planned however.

Even friendly villages encountered are unlikely to have sufficient food to trade, preferring to hide stockpiles in reserve for proof against marauders and the coming of Winter. Larger towns may have food to spare but even they are more likely to trade distilled fuel eg methanol and only trade food if they have a particularly bountiful crop in the Fall and the group has earned the inhabitant's trust or has assisted in either the planting or offers to use their vehicles to help with the harvesting.

Buying pre-war rations (MREs and similar) becomes difficult as the are quickly used up, but canned and processed domestic food from larger towns and the emerging free cities makes for an expensive backup at $4 per kg as many cities trade *for* food to feed their larger populations so charge a premium. Most domestic food has the advantage of not needing refrigeration or freezing to preserve it.

Bartering is an option to be sure, but a potentially limited and expensive one.

Conclusions for Simplified Play

For the first 4 months of a beginning campaign (assuming the Escape from Kalisz default start), foraging off the land in Woods or Hills is sustainable for a small group, whereas travelling by road or river through clear terrain such as Meadows usually requires a previously secured food supply and more than a single period a day foraging per character unless consistently supplemented by fishing and/or hunting, which is a significant gamble. Obtaining a reserve of food should therefore be an early goal and drive opportunities for stories for the group such as interacting with villages for trade, raiding a supply dump or heading towards a larger settlement for trade.

Larger groups require a lot more effort to love of the land and if travelling in vehicles run the risk the change of depleting their surroundings if they need to be stationary for long periods - the "stuttering" travel / distil / travel pattern for vehicles with insufficient fuel supplies using stills to replenish fuel as they travel creates this scenario easily. Even if travelling through Woods/Hills at least half the group must forage for at least one 4-hour period per day to allow for subsisting on half-rations and larger groups must split up and provoke additional encounters as the area surrounding camp becomes rapidly depleted. This provides the opportunity for interactions with individual characters and their stories in contrast to group activities but this increases the element of danger. Hunting becomes more attractive as a choice but requires moving through Woods and Hills to be most effective, and stealing food from civilians or raiding Fields is understandably a strong temptation in clearer areas. Larger groups simply cannot reliable live off the land when travelling through Meadows (or Swamp) areas and may therefore need to resort to raiding villagers if hunting is insufficient.

Fishing is useful to supplement food stores in Summer and Autumn and is worthwhile trying whenever appropriate slow moving water is nearby, but is only really a primary option for a small group travelling in Winter and Spring and still needs to be combined with reduced effectiveness foraging and limits travel to areas where slow moving water is common.
Once Winter sets in, living off the land is very difficult except for a small group of characters with highly developed Survival Assets, and becomes very time consuming. Raiding fields is no longer an option and bartering for food is less common as villagers are reluctant to part with their stores. As Hunting doesn't change seasonally, it becomes more useful to consider as an option. By Winter, a group without a secured food reserve is at risk of starvation which may provide the desperation needed to drive stories in the direction of conflict and force moral choices upon them.

Harvesting (or raiding) fields, grenade fishing, hunting and bartering are all useful to supplement food stores but are all either uncommonly available, unreliable or expensive in terms of resources. When the opportunity arises however they can each provide a potential surplus to create a reserve of food or boost the group from consistently needing to survive on half-rations.

Preserving and storing food is simple enough, although a group relying on refrigerators and/or freezers for their excess food need to maintain their power supply, and the whole setup is bulky enough that it needs to be transported by vehicle.

Overall, starvation prevention shouldn't be a chore but provides several story opportunities - the reality is many groups will spend a significant amount of time half-starved and food should be an early game resource issue, but resolves if the story of surviving Winter can be successfully negotiated and only invoked as a crisis or to drive the story in a particular direction.