On RPGNet, someone asked to be "sold" on OD&D. I kind of hate the idea of "sell me on" threads, but that's beside the point. I decided to post my reasons for preferring OD&D over other versions. I've probably said all of this before, in individual posts over the years, and I've probably missed a few tiny things I just like better in their original implementation, but I think it's still worthwile to archive the reasons here, in one post.
- It's simple. None of the later penalties and bonuses listed for every action or situation. That's a big deal because I tend to run D&D as "whoever has the advantage gets a 1 or maybe 2 point bonus, period". Which means NO LOOKING UP RULES. Similarly, it urns out all those scattered "1 or 2 in 6" or "1 to 4 in 6" chances of something happening can be summarized as "1/3rd chance things will change from the current situation, with an occasional +/-1", so you don't need to look THAT stuff up, either.
- All weapon damage is 1d6, all hit dice is d6. 1st level characters are all basically the same in combat, except that fighters get +1 hit point, so that means that M-Us aren't really "useless" after they've cast their single spell, or before they've cast it, for that matter. It's more about what any human could do in a situation than it is about special snowflake powers.
- Because all classes use the same hit die, just different hit die progressions, and the monster combat table basically breaks down to +1 to hit for every +1 hit die, you can switch to Target 20 for combat and simplify it down to "roll d20, add hit dice and AC of target, 20+ = hit". It works out pretty much identical to the original, so that means one less thing to look up. You can even maintain some mystery by having players roll the d20 and add their hit dice, tell you the total, and YOU secretly add the AC to see if they hit.
- Monster stats, excluding special abilities, all fit on one line, so a one-page table can hold a ton of monster varieties.
- No bonus inflation. Defensive bonuses don't add (Armor +1 and Shield +1 is not equivalent to Armor + Shield + 2.) Rings of Protection don't "stack" with armor. Ability score bonuses, where they even exist, are rarely more than +/-1. The exceptions are capped at +3, and the same applies to magic weapon and armor bonuses. No obsession with getting all 18s and super weapons and armor, one less thing to look up, and no one is invulnerable.
- No ability score minimums for either class or race. You want to play a STR 3 Fighter? Go for it. You'll advance slower, but it has no effect on the character's playability. You can be anything you want.
- The social rules (reaction rolls, morale, material on hirelings) take up more space than the combat system. There are even rules for designating an heir.
- Simpler spells. The descriptions are short and can even be ignored, just improvising based off the spell's name. There's no "casting time" or "material components" at this point, and very few spells have features that improve with caster level, so there's not much that needs to be written down on a character sheet.
- No extra garbage. Really, the problem with a lot of later stuff is there's a lot of it, all written down and well-known and therefore easy to argue about when one GM refuses to allow this or that. No wading through the rules to figure out which to keep and which to dump, unless you really want to... and even then, the books are so small, it won't be hard. It's not so much that the rules are focused on the dungeon crawl as it is focused on jumping right into whatever fantasy environment you want, even to the point of leaving most of the world a blank page until you're ready to explore.