I heard about this latest RPG blogosphere meme at The Other Side blog and others.
So here are the RPGs that I've played the most, in roughly the order in which I played them (with some overlap, of course):
1. First Edition AD&D
The game that got me hooked, just like so many other roleplayers! I loved the arcane language of Gygax (as a kid I used to wonder, "who is this mysterious author with the strange name?!"), and the sometimes crude but always evocative illustrations. What times my companions and I had with those books!
2. Palladium RPGs (Teenage Mutant Ninja Turtles, Ninjas & Superspies, Heroes Unlimited, Rifts)
Ah yes, Palladium! I may cringe a bit now at the thought, but back in my formative years Kevin Siembieda almost loomed as large in my mind as St. Gygax! We created many mutant animals, superheroes, master martial artists, and post-apocalyptic adventurers in those days. But eventually, especially when it came to Rifts, we nearly drowned in the sheer number of sourcebooks!
3. Second Edition AD&D
We "graduated" to Second Edition eventually, and I really liked the more "professional" color illustrations, the different presentation, and the various published worlds that came along with this edition. I don't remember being bothered that they removed/changed the names of the demons and devils, or that the monk and assassin were gone (no one in my teenaged group ever played them). But I hated the Monstrous Compendium (those pages always wore out and fell from the unwieldy binder! we just kept using the First Edition Monster Manual!).
4. Amber Diceless RPG
I moved to this game when D&D became too "childish" for me. It also helped that Erick Wujcik of Palladium fame was the creator. I considered the game more mature, due to the lack of dice and what I considered a subsequent focus on roleplaying. It also introduced me to Roger Zelazny's body of work. Besides 1E AD&D, I probably had the most fun playing this RPG during my first era of roleplaying.
5. Castles & Crusades
The game that brought me back to table-top RPGs! I owe the Trolls a debt of gratitude. The game is an incredible "reimagining" of 1E AD&D by way of 3E!
6. Savage Worlds
I've only played this RPG a few times, but so far I really love the mechanics.
7. Labyrinth Lord
The game that's made me regret that I never played Classic D&D back when I was a kid. I've only played LL a handful of times, but it's opened my eyes to the wonders of the era when races were classes!