OSRIC (Old School Reference & Index Compilation) offers a free fantasy role playing game inspired by first edition Dungeons and Dragons. It’s not the first effort I’ve seen trying to recapture the magic of 1st edition, before the life was sucked out of it with the bloated later editions.
Dungeon Quest is a free old school fantasy RPG.
There are a lot of people out there trying to recapture the spirit of the original D&D games. For my own part, I can think of nothing that was more magical than my first excursion into the blue covered rulebook I got back in the late 1970s/early 1980s. Old School Hack is another attempt.
Free for the downloading, Spellcraft and Swordplay is a professionally done “old school” fantasy RPG.
Dark Dungeons is a clone of the old school D&D game. There’s been a real renaissance in the retro style RPGs, and its one I welcome after all those years of angst ridden vampires and new-style gaming.