I know I’ll never fully embrace OD&D because I hate using charts. I prefer simple, easily internalized rules, like 3e’s Base Attack Bonus, rather than 1e’s Attack Matrix charts. 4e’s XP system still has a big ol’ level-advancement chart at the center of it, along with XP entries for every creature in the Monster Manual (which I often don’t use).
The 4e XP system has been formalized and math-checked, which means one of D&D’s central problems is more obvious than it has ever been: it suffers from “inflating-numbers-that-don’t-do-a-goddamn-thing-itis.” At level 1, you fight 10 battles in order to collect 1,000 XP. At level 10, you fight 10 battles to collect 20,500 XP. The specific amount of XP per battle changes, but the number of battles doesn’t.
There’s a historical reason for that. In old D&D, your XP was tied to your income. Since high-level characters won richer and richer treasures, XP totals per level had to rise. Now that characters don’t get 1 XP per GP earned, however, there’s no reason that XP needs to stick to that inflationary model.
Besides, calculating XP is kind of a pain: it involves flipping around in various books to add XP from monsters and traps, and dividing by the number of PCs.
I can’t be bothered to calculate XP, but I’m not ready to totally dump the idea of leveling up. Having the DM bestow levels arbitrarily takes away some of the treadmill charm of D&D. So here’s the super-simple XP system I use nowadays.
Every level costs 10 XP.
Most battles provide 1 XP. Boss battles provide 2 XP.
Same with quests and skill challenges: 1 XP, or 2 XP for major quests/challenges.
There are some minor variations here from the standard XP system: