From the Introduction
Searchers of the Unknown is a one-page roleplaying game where player characters are entirely defined by a minimalist old school Dungeons & Dragons one line stat block (e.g. "AC 7, MV 9, HD 2, hp 9, #AT 1, D 1d8 mace") something like monster stat blocks in early editions of D&D. All actions are based on those stats. Armor class is the old school “lower is better,” but the way armor class is used in SotU it makes sense with armor class generally helping against attacks but hindering initiative and attempts to be stealthy. The basic SotU generally uses a level plus AC roll under mechanic, using an opponent's AC when attacking or the character's own AC when trying to be stealthy. Saves require a roll under level plus 4. Variants versions of SotU use D20 or Target20 rolls. In the basic game, all characters are human adventurers. Supplements add demi-humans and spell-casting classes.
Like Microlite20, the original Searchers of the Unknown rules inspired a large number of similar games based on the same principles, ranging from simple variants like SotU Refired to modern day games, science fiction games, after the holocaust games, etc. Most of these games are complete in one or two pages. A few have additional supplements of their own.
This is a 56 page compilation of SotU based games. It is well worth the time it takes to download. It actually looks playable, as well as fun. The basic rules take up the front of one page. (This would be an excellent candidate for a pocketmod . . . ) The stat line format for characters makes it instantly compatible with virtually everything pre-AD&D right out of the box, including clones thereof. AD&D wouldn't be a hassle, either, just not quite as automatic.
So, download it and give the basic rules a read. It will be 10 minutes well spent. Many thanks to Randall over at RetroRoleplaying: the Blog for putting it all together. Be sure and go by his blog, he has a ton of great stuff on offer, not to mention insightful commentary on gaming and the OSR.
Searchers of the Unknown