|This is your new tabletop.|
Not what you're thinking.
These super-complicated games that are being sold these days don't seem like they'd be really useful in such a situation. If I need a thick hardcover book full of charts and lists of feats and whatnot, that's something I have to lug around that weighs a lot and doesn't contribute much to my survival (though it would contribute to my life). What happens if I lose it? As an aside, wargames with fiddly sets of counters or plastic miniatures aren't much use. We need wargames that can be put together without much more difficulty than chess or shogi. That bears thinking about, too, but it's beside the point for this post.
Let's assume that I can have a d6 or three and a d20. From there, it's easy to put together an OD&D variant based on, say, Original Edition Delta, LotFP, and S&W:Whitebox. Classes are easy: fighters start at 2000xp for 2nd level, magic-users 2500xp, clerics (if you have them) 1500xp, thieves 1200 or 1250xp. Then double that amount at each level gain. Hit dice are in d6, each level for fighters, 2 for 3 levels for clerics, 1 for 2 levels for magic-users and thieves. Fighters get a bonus hit point at first level, other classes get a bonus hit point at levels they don't get hit dice (the bonus point goes away at the next level that gains a hit die). Combat is simple: a d20 plus the attacker's hit dice and plus the defender's armor class for 20+ to hit, 1d6 for damage (1d6-1 or roll 2d6 and take the low for light weapons like daggers, 1d6+1 or 2d6 and take the high for two-handed weapons). Saves are d20 plus level plus 4 (plus 5 for fighters) for 20+. Each class except fighters get a bonus of 2 in a single save category (spells for magic-users, thieves for devices such as traps or wands, clerics for poison or paralyzation). Thieves get 4 skill points at first level and 2 skill points at each further level, which they can use to add to any of the skills. Everyone gets all skills at 1 chance in 6 (meaning 6 on a d6, or 1 on a d6, or x1 damage for sneak attacking). The skills are: Climbing, Searching, Find Traps, Hunting/Foraging, Languages, Sleight of Hand, Sneak Attack, Stealth, Tinkering. Foraging and Hunting are affected by the terrain, from base 0 in 6 in desert, 1 in 6 in mountain or swamp, 2 in 6 in plains, or 3 in 6 in forest or jungle, each skill point increasing the chance by 1 in 6. In the desert, water can only be found on 1 chance in 12 (roll 2 d6, the first as even = 0/odd = 6, or low = 0/high = 6, the second as a regular d6), each skill point adding 1. Fighters get to attack once for each level if the opponents are 1HD.
The difficult part is remembering the details of spells. I still need to think about a good way to do those.
Anyway, experience points are 1 for each gold piece (or silver piece) recovered. Also 100 experience points for each HD of defeated enemies (or a more complicated way of doing it that goes from 5xp for a <1HD up to 1000xp for a 16HD creature or whatever, but this is probably too much effort). Special abilities add 1HD for this purpose each.
Stats are equally simple. Each one is 3d6, with a 13+ giving a bonus of +1, and a 8 or less giving a -1 penalty. If the characteristic for the class is 13+ (Str for fighters, Int for magic-users, Wis for clerics, Dex for thieves), gain +5% experience earned, plus the same bonus for Wisdom of 13+ (clerics count this twice), and again for Charisma of 13+. Charisma also has a number of followers equal to a base of 4, +1 at 13-15, +2 at 16-17, +3 at 18, -1 from 6-8, -2 from 4-5, -3 at 3. What the stats bonuses are used for varies by DM (except Charisma is always used for reaction and loyalty/morale checks). Reaction rolls are made on 2d6: 2-5 negative, 6-8 uncertain (will follow others if there is a plurality or majority), 9-12 positive.
Personally, I'd dump clerics (too much to remember two spell lists and two spell progressions). I don't know about thieves. The LotFP method is fairly simple, if there could be an easier way to remember their nine skills.
Encumbrance should probably be in some version of stone encumbrance (where each stone is 10-15 pounds of weight), so that a weapon carried so it can be easily used is 1 stone, light armor (AC7) is 1 stone, medium armor (AC5) is 2 stone, and heavy armor (AC3) is 4 stone. A shield (1 point bonus to AC) is 1 stone. 5000 coins is 1 stone. There are also bundles, 5 to the stone. A weapon carried packed away is 1 bundle, or 2 bundles for two-handed weapons. A character can carry Strength in stone at 3" move, half (round up) that at 9", halfway (round up) between the two at 6", and up to a quarter (round up) of Strength at 12". So, at Strength 10, a character could carry 3 stone at 12" move, 5 stone at 9", 8 stone at 6", or up to 10 stone at a rate of 3". Of course, someone could change the AC to ascending, but whatever.
So, here we are, coming toward a bare bones approach to roleplaying, using D&D as the basic framework. I can think of other, even simpler, approaches, but this one is a pretty damned good one, I think. If only I could find a good way to handle magic-user spells and spell progression. Maybe it would be better to take a page from The Arcanum and allow a magic-user to cast a number of spells equal to level plus one per day, limited to a spell level of the character's level divided by 2, rounded up. Still need to have the spell lists somehow, but that might be the best way to go.
Maybe later on, if I see any interest in the idea, I'll talk about some other simple roleplaying games that we could play in the post-apocalypse. Risus is an example, and there's a version of EABA designed specifically for playing while hiking, but I could talk about my own Trait System too. If you have any ideas or interest in the subject, please comment!