Finding out what gamers are like

[Stormonu]

Alternity/Dark Matter, Gamma World, Star Frontier, Star Trek, Twilight 2000, Battlestar Galactica/Serenity/Cortex, Chill, Paranoia, Legend of the Five Rings, Seven Seas, Pendragon, Spycraft, James Bond 007, Top Secret, Boot Hill.

Granted, some of these are out of print, but some folks still play it.

 

[Neonchameleon]

Original D&D
BECMI (rules cyclopedia D&D)
1st edition AD&D
2nd edition AD&D
3rd edition D&D
Pathfinder
4th edition D&D
Ars Magica
Babylon 5
Barbarians of Lemuria
Big Eyes, Small Mouth
Blue Rose
Call of Cthulhu
Conan
Cyberpunk
d20 Modern
Deadlands
Dragon Warriors
FUDGE
GURPS
HERO System
Kult
Mutants and Masterminds
Palladium
Rolemaster
Runequest
Savage Worlds
Shadowrun
Star Wars
Storyteller
Traveller
Warhammer Fantasy Roleplay
Zenobia

Looking at that list it skews old and a few obviously missing major-ish modern ones:

Fate. (No, Fudge isn't Fate. Fate just uses an engine borrowed from Fudge).
Cortex Plus (Smallville, Marvel Heroic Roleplaying, Leverage, the forthcoming Firefly RPG). Possibly merged with Cortex (Serenity RPG, Supernatural, Cortex itself) although the two have very different approaches.
Fiasco
Apocalypse World and co (Dungeon World, Monsterhearts, Monster of the Week, Tremulus, many many homebrews)
Gumshoe (Trail of Cthulu, Ashen Stars, others).

Also do you have anything from the One Roll Engine on there?

 

[Dethklok]

One thing you have to remember is that each rpg in the list is another button someone has to click indicating their opinion of it. So in retrospect, I probably included too many RPGs, since most of the respondents don't know most of the games in the list! It's always possible to write in new or obscure favorites in the comments field.