I can't believe this hasn't been mentioned yet, but Desktop Dungeons [http://www.desktopdungeons.net/] uses the mechanic that, for each square of the dungeon you explore, you regain an amount of life equal to your current level. (as do all the other monsters in the dungeon, except based on that monster's level!) There are potions, but they are to be used as sparingly as possible, as you can't save them up between dungeons, and you can't guarantee you'll end up with all that many of them (even if you pick a race that can create them). If you like dungeon crawlers and you haven't played this yet, you really have to, it's one of my favorites, and addicting though it may be, if you can restrict yourself you can get a rewarding game session from only about 10 minutes, as that's the amount of time you'll generally spend on each dungeon.