This article over at Gnome Stew got me to thinking about this, and I thought it was interesting enough to do myself. Anyone who has been reading the blog for any length of time can probably figure out most of them but I wanted to go through it myself and see if there were any surprises. I'll do the "played" today and the "GM'd" tomorrow.
The 7 Games I've Played the Most: (this assumes "DMing" doesn't count as "playing")
1 - AD&D - I spent a LOT of time on this one, getting my DMG about 1980 and the rest of the books the next year and a regular set playing group the year after that - one that stuck around for decades. This was THE game for me in the 80's, all others were secondary, and I obsessed over it like nothing since.
2 -AD&D Second Edition - Yeah this kind of surprised me, but we had a full 11 year run on this as we started the day it came out in 1989 and played it regularly until the 3rd edition launch in 2000. The center of this time was a nice long ongoing campaign set in the Forgotten Realms that a friend of mine ran pretty much this entire run, which was basically "the 90's".
3 - Gamma World - I'm cheating a bit by lumping all editions together here but it was really one ongoing campaign that started in 2nd edition with one set of characters about 1983 and continued through 3rd edition (convert and move on!) and 4th edition into the 1990's. Run by the same friend, this was set from the ruins of Louisiana up to the Great Lakes over the years.Part D&D, part Western, part Superheroes, we had a lot of fun with this game.
4 - D&D 3rd Edition - I'm going by hours here, as over the years I played this quite a bit but never in a good long sustained campaign. Added up it's probably the fourth most-played game but it tended to be in very small chunks here and there. The biggest problem here is that I was running so much I didn't have time to play
5 - Mechwarrior - I am again lumping all editions together here. This game came out in 1986 and we jumped on it immediately, having a fondness for the giant robot war story campaign that never really went away. Again, a friend of mine ran it, and a group of about 4 of us played it in sustained bursts for 1st, 2nd, and 3rd editions, through the original succession wars, and into the clan invasion. We painted the mini's, read the novels, and waged war on a planetary scale at times. Most of our Battletech games were tied in to our Mechwarrior campaign, wherever it happened to be at the time. It's a whole different way to play the game as having to consider "what happens next" gives one a different perspective on combat, from character fates to repairs, to transportation - it was a lot of fun.
6 - Twilight 2000 - I was pulled into a campaign of this in the late 80's run by one friend and it became a regular part of the rotation with another friend running campaigns of it as well. It's a fairly realistic game - there are no magical healers, radiation kills you instead of granting superpowers, and there are no giant robots, zombies, ninjas, or wizards.It's just a group of relatively normal humans trying to make their way in a broken world. Overcoming those challenges makes for a fun game though not everyone likes that kind of thing. We played 1st edition, 2nd edition, 2.2 all back forth from about 1987 into the 90's and even had a short run of 1st edition just a few years ago.
7 - Star Trek - Fasa edition. Besides the various D&D's this is the only entry that covers only one edition of a game but it was a lot of fun. Creating a single character and running him over most of a decade (on and off) is something I have not done before or since. There have been other Trek games but this is the only one I experienced as a player.
After this we get into a long tail of Traveller, Boot Hill, Marvel Super Heroes, Champions, Shadowrun, Warhammer FRP, Rifts, Gurps, B/X D&D, Star Wars, 4E D&D etc. I've played a lot of games but the ones listed above form the core of my playing experience. One thing should be clear from the above: There is always a D&D game, then are the side games or temporary diversions. I don;t expect that will change anytime soon.