Delta's latest post got me interested in OD&D, particularly his mention of a movement point system. The whole "miles per day with multipliers that don't work out to even numbers of hexes" has been a thorn in my side before, so I'm really curious to see what came before it.
Reading Chainmail first. As usual this is a collection of notes on things that surprised me while reading.
Part 1: Mass Combat
One figure represents 20 guys, and one inch of table is 10 yards. Looking at the pictures before the introduction, it looks like groups of 20-30ish figures were the norm, or about 400-600 guys per large block of troops. So the whole battle was probably around battalion scale, in Domains at War terms.
I love that secret orders with simultaneous movement is an option - Domains at War with secret orders and simultaneous movement would be interesting.
Movement rates are already of the form 6/9/12 for armored, heavy, and light foot.
Tracking fatigue for individual units, oh dear.
It is interesting that fatigue kicks in after 4-5 turns of action, after which you need a rest turn, and fatigue makes units attack, defend and roll morale one step worse. Which sounds suspiciously like dungeon fatigue, where you get 5 turns of action followed by a rest or you take -1 to hit and damage.
Using a painted dowel to resolve cannon fire.
Morale is big, obviously.
No firing into melee.
Crossbowmen can't volley overhead.
Landsknechte seem to get a bunch of bonuses?
Knights have to roll obedience or charge any enemy within charging range (preferably enemy knights).
Mercenaries can demand more pay or defect mid-battle.
Peasants have to roll before attempting basically anything.
Religious order knights never surrender.
English longbowmen can plant stakes to ward off cavalry.
Mongols recover from retreats (but not routs) automatically.
Polish troops have elite morale.
If enemy units get near your table-edge they can loot your camp.
I like the weather state-machine, and the influence of heat on fatigue.
Part 2: Man-to-Man Combat (shifting the scale from 20 guys per figure down to 1 guy per figure):
I don't see a ground scale for man-to-man combat (where each figure represents just one guy) mentioned. If you have 20 guys per 30' square, with one guy you'd expect 30' * sqrt(1/20) or about 6.5 feet per inch. So looks closer to a 5 foot square than a 10 foot square, and engaged in melee is within 3 inches or about 15-20 feet.
Crazy rules about how the relation between the reach (rank) of the attacker and defender's weapons determines who strikes first and how many attacks they get. Between this and the weapon-vs-armor table, picking weapons seems like it would matter a lot.
Parrying! Forfeit your attack to give someone attacking you a penalty to theirs. Naturally weapon reach/speed plays into whether and how effectively you can parry.
Berserkers appear here; I guess you just can't get them in bulk.
Part 3: The Fantasy Supplement
Dwarves and Gnomes are equivalent, as are Goblins and Kobolds. Even here dwarves have darkvision (and this is the origin of the "giants have a hard time hitting dwarves" too), but elves don't. Elves can all turn invisible and have magic swords that wreck orcs and goblins, but use different mechanics from human magic swords. Hobbits "have small place in the wargame", can blend into terrain, and can throw stones as well as an archer shoots / to the same range which is wild.
Orcs are "nothing more than over-grown Goblins" and have to pass an obedience roll or start fighting other orc warbands within charge range, even if they're on the same side, unless already engaged in melee.
Heroes fight as four normal men (hence 4th level fighter's level title and the breakpoints for to-hit in Basic, presumably) and super-heroes fight as 8 normal men. They can also just... shoot down flying dragons (with a low chance, but it's all-or-nothing for each individual shot). Rangers are slightly better heroes - this might be the origin of ranger as a weird special class that you had to become rather than something you could start as.
Various levels of wizard; they have different penalties to casting depending on how strong they are, but all fight as two normal men and are impervious to normal missiles. Fireball and lightning bolt are both save-or-die (but you have to pre-declare a range, like artillery fire in Warhammer 40k, so they're easy to miss with) and dragons don't give a fuck about either. Counterspelling is a totally normal wizard thing to do. Phantasmal Forces creates an illusory unit. Haste doesn't give extra attacks, just more movement speed to a unit (likewise Slow just lowers movement speed). Confusion interacts with secret orders. Cloudkill drifts at random if not concentrated on. "In order to cast and maintain any spell, a Wizard must be both stationary and undisturbed by attack upon his person." The Number of Spells table says "The power of the magic user determines the number of spells he is able to manage:" This is ambiguous - number of spells known, or number of simultaneous spells he can concentrate on? Presumably the former but the latter would be an interesting alternate direction to have taken magic in D&D.
Optional rule for rolling to cast may have the spell fail, or it might just be delayed a round, which the wizard has to spend continuing to concentrate. The six degrees of spell complexity look like the beginnings of the spell level system.
Wraiths are very ringwraith and paralyze any normal man they touch; paralysis persists until touched by a friendly Elf, Hero, or Wizard, which rather reminds me of freeze tag / capture the flag. Lycanthropes are only werebears and werewolves, and when near forest terrain they get bonus attacks from allied beasts.
Troll / ogre distinction is muddy and they don't regenerate, but they do fight as six normal men. Their hit points are ablative though - six cumulative hits, whereas heroes need four simultaneous hits in a single round to be killed. That's a really interesting distinction. Hit points are great as a resource that can be ground down in dungeoneering but having damage be all-or-nothing / non-cumulative ("it takes 18 damage in a single minute to kill a 4th level fighter") is another strange direction D&D could've gone, like magic users concentrating on simultaneous spells. True Trolls can only be killed by fantastic creatures but aren't very good at attacking normal men. Giants fight as 12 men with cumulative damage, can throw rocks like a light catapult, and never check morale (except when hit with fireball or lightning bolt).
Dragonbreath is also save or die, and it's not three times per day - it's three times before they have to land and "remain stationary for one turn in order to rekindle his internal fires." Dragons also attack other fantastic beasts regardless of side, and are immune to normal weapons and missile fire.
Wyverns, griffons, and rocs are all under one entry and can transport a single man-sized figure, so presumably these rocs are more like Tolkein's giant eagles than the roc of Arabian Nights. Djinn and efreet are just normal elementals. Wights and ghouls are in the same entry; they are immune to normal missiles, their paralysis lasts one turn, and you get a chance to attack them first. Zombies are a subset of wights and ghouls but slower; they fight as orcs, but I can't seem to figure out what orcs fight as against normal men? Ah, it's on the table, as heavy foot. That's sort of interesting, that orcs don't fight significantly better than humans.
Weapon vs armor table. Weirdly, the single-man scale missile fire rules basically have ascending AC - "Class of armor worn by defender", from 1 to 8, with 1 corresponding to No Armor and 8 corresponding to Plate and Shield. So it's really surprising to me that we somehow got to descending AC from here, and then back to ascending AC later.
In conclusion: I'm amazed that we ended up with the D&D that we did given this starting point. I love how all these units are unreliable in their own special ways; knights having to charge, mercenaries defecting, peasants cowering, orcs fighting each other, dragons fighting other beasts regardless of side. It seems like it would lead to unpredictable but hilarious games.