Fickle RPG is
a narrative roleplaying and cooperative storytelling game, distinguished by the core dice resolution mechanic which has bluffing, bidding, and meaningful decisions. The game is a universal system that can be played in any genre, such as sci-fi, military, zombies, high fantasy, superheroes, etc. An ongoing campaign can be played over multiple game sessions, or as a themed one-shot.
Lizards vs Wizards is an RPG set in the “days after the Big Blammo.” You are a sentient lizard. Unfortunately, there also are Wizards, who are “crazy, weird and dangerous humans” who often use lizard parts in their experiements.
It looks like a hoot.
Explore Alterra is a tabletop RPG that eschews a character sheet in favor of cards that measure spells, weapons, armor, talents and items. It is a very straightforward system, and an interesting setting.
Steve Jackson’s GURPS (Generic Universal Role Playing System) is one of the grand old men of the role playing world. The game provides one of the most realistic, detailed gaming systems ever. Because the combat system is so good, I know of many miniature gamers who use it for skirmish games. Steve Jackson games has released a free “lite” version of the rules as a pdf download.
Tombstone is a free RPG set in the wild west. It’s designed to be rules-light, and has quick play character creation to get you started.