This is a list of tabletop RPGs (mirrored from the No Time To Play website) that have attracted my attention one way or another. That doesn’t mean I like all of them! I have omitted games that no longer have a home on the Web, and most commercial games. More exhaustive lists are pointed out at the bottom.
Risus is a tiny (only six pages for the core rules!) RPG based on extremely simple dice pool rules. A variety of supplements exist, some commercial, by the same author, some fan-made. Free for personal use; derivatives allowed.
Sacred Steel, a once-lost fantasy RPG, brought back to life through the miracle of free culture.
The Window, an elegant ruleset designed for grittiness, suspense and horror, that skimps combat in favor of story. Free for personal use.
Shadows, an RPG for kids, with a simplistic but interesting conflict resolution system. Free for personal use.
Sherpa is a little RPG by the author of FUDGE, designed to be used on the go. Unusual randomization device. Free for personal use.
Puppetland — highly original RPG with unusual mechanics. Freemium.
Shadow of Gilgamesh / Swords and Lanterns were two retro minimal games with unusual rules; the former even allowed solo play.
Pirates! is a simple RPG for cartoonish piratical adventures that make Captain Sparrow seem realistic in comparison. In English and French.
Troika!: a quirky, exotic and quite possibly postmodern RPG with a free edition. See also the RPG.net review.
Skyfarer: based on the videogame Sunless Skies, itself set in the world of Fallen London (that I reviewed back when it was called Echo Bazaar). Steam, supernatural and strangeness.
Uncharted Worlds was a flavorful space opera ruleset under a CC-BY-SA license.
The Star Wreck RPG, a goofy inversion of space opera tropes… and also RPG tropes: the heroes are fighting their own incompetence rather than any serious enemy. CC-BY-NC-SA.
Mazes&Minotaurs started out as a bit of a joke, and was defictionalized so skillfully, it turned into quite a serious thing. No license specified, so, free for personal use?
FUDGE is a flexible RPG system toolkit based on attribute ladder. Uses very unusual “FUDGE dice”, but can make do with ordinary six-siders. Freely redistributable; anyone can make supplements.
FATE is an RPG system based on FUDGE. It features character creation based on organic growth, several magic systems, several ways to resolve combat and so on.
Sword and Sphere was a retro sci-fi sourcebook for Fate, having Mars as a theme. CC-BY-SA.
Tri-Stat dX, the rule system of the highly regarded games Big Eyes Small Mouth and Silver Age Sentinels is free for personal use. Detailed list of superpowers and skills; very complete and flexible rules.
Mini Six is a very condensed version of the OpenD6 rules. The core book tries to squeeze a magic system and several settings in only 38 pages, with poor results. Open Game License.
The fan supplement Rocket Rangers used to bring an excellent retro-sf setting to Mini Six.
GURPS Lite: the oldest generic RPG system condensed to only 32 pages. Freely redistributable.
CthulhuTech, a crazy world combining mecha, magic and otherwordly horrors on a vaguely cyberpunk-ish backdrop. Original dice pool mechanics. The Quick Start Rules used to be freely redistributable.
Engine Heart — the humans are gone; only their robotic servants endure. Intriguing setting, somewhat dubious (dicepool) mechanics.
Basic Fantasy: comprehensive OSR (old-school revival) game with many translations, supplements and such, plus an active community. Open Game License.
Classics gone free
Star Frontiers (warning, 1990s website layout!) is a generic, but good space opera RPG from the 1980s. If you remember the Xindi story arc from Enterprise, the alien races were swiped from this game. Comes with detailed rules for space combat.
Talislanta has built its reputation on having a very original fantasy world, nothing like the more common Tolkien-esque cliches. Unfortunately, it tries so hard to be different, the results are often ridiculous. YMMV, though.