I stole an edited Ulfgeir's list. Thanks to him for doing the work
* (Advanced) Dungeons & Dragons (1st, 2nd (Ravenloft, Dark Sun, Spelljammer, Plansescape, Forgotten Realms, Greyhawk, Red Steel, Council of Wyrms), 3.x, 4rth edition)
* BESM
* Buffy the Vampire Slayer
* Call of Cthulhu
* Changeling 2nd edition (more accurately a Changeling char in a mix of all WoD-systems availible at the time. I believe we had 1 western changeling, 1 asian vampire, 1 mage and 1 werewolf).
* Cyberpunk
* D20 modern
* Dresden files
* Dungeons & Dragons (basic version)
* Exalted 2nd edition
* Fate Core (oneshot in Dresden Files campaign)
* GURPS (3rd, 4rth edition) - Various settings
* Marvel Super Heroes
* Mutants and Masterminds (2nd edition, DC Universe)
* Pathfinder
* Runequest (played once on a convention)
* Savage Worlds
* Shadowrun (1st-4rth edition)
* Star Wars (d6 + D20: revised edition + Saga edition + Edge of Empires)
* The Dying Earth
* Vampire: the Masquerade
* All other Old World of Darkness Systems.
*Mind's Eye Theatre. The Old World of Darkness LARP
*MechWarrior
*SOIF RPG (Song of Ice and Fire)
*Everquest D20
*Dragon Age
*Hercules and Xena Role Playing Game
*Battlestar Galactica - was a dismal failure
*World of Warcraft TT D20 I'm pretty sure, only played once
*Palladium
*Star Trek - was a dismal failure
*Scion
*New World of Darkness (pretty much all of it)
*MEGS superhero system (Originally called DC Heroes)
*Champions
*Hackmaster - which is just a cross between Original D&D and AD&D with a humorous bent and a few new rules
*Too many homebrews to count
As far as playing now. 2nd Ed. AD&D. A MEGS system. Soon to be D20 Star Wars. Then likely more SOIF and Dresden Files RPG.
Of course playing other games effects how you play other games. People who prefer story or narratives to dungeon crawls will play games that are traditionally dungeon crawls more like a drama. People who prefer dungeon crawls and hack n slash will play narrative games with more combat.
I'm certain our DFRPG is a little more combat and action heavy than others, but my group still likes a good long roleplaying and narrative session. In my mind we cultivate3d a pretty happy medium. Not every group wants or likes that.
When you have been gaming in this fashion for a long time - I'd say in excess of five years and have a well defined and diverse palette, you will game differently. It compounds when you have been doing it for decades.