-. Knights of Legends - original C64 game in it's original box... cant get rid of it, just in case i'll ever go back to playing c64 again 
-. MechForce - Amiga (wow talk about favorites, I still carry around printouts of my mech configurations, just in case... Funny as this was also the very first piece of shareware I ever encountered, it was never fully finished I think as FASA interfered or something cant really remember. Still know the programmers name by head... Ralph Reed)
live changing games, hmm... hold on lol...
Avalon - a PBM (play by mail (thats snail mail folks)) fantasy game originally developed by an english company that went bankrupt but further extended and developed by a Dutch company named the PBM Express (now sells collectible merchanise as far as I can tell). I still own all maps I made for that game and all my turn printouts lol (100 players per game), managed to win the very first game of that after 3 years of playing lol. Ended up working for the company as a GM (gamemaster) running games like railroad tycoon and SuperNova pbm games.
Genre wise, games I played to death and would still play today (heh they still get me all giddy just thinking about them);
-. Settlers - C64 (ended upgrading to Amiga to get a more stable version of it)
-. UFO: Enemy Defense - Amiga (lovvvvvvvved the tactical AI and setting of the game)
-. Civilization - Amiga (ended up upgrading to PC to get more stable version of it, loved the xbox 360 remake Civilization Revolution)
-. Rogue - PC-XT
-. Command & Conquer - PC (discovered this game whilst backpacking through Australia, ended up playing in pay per hour for pc usage shops all throughout Australia, never got into later versions of it when back home we also reverted back to C&C:Gold untill RA2 came out, been steady top 10 player in the world for that for over it's first year).
-. Railroad Tycoon (Sid Meier) - PC
-. Rollercoaster Tycoon - PC
-. Megalomania - Amiga
-. Settlers of Catan - Xbox360 (still play that on a daily bases, ranked 28th in the world as i write this)
-. Battlefield: Bad Company - xbox360 (finally a shooter I like)
-. I also enjoyed my share of point and click adventures, but dissed them all once i played through it once, titles that spring to my head are Sam & Max hit the road, day of the tentacles, euhrm the 4 cdrom PC movie like game where you played a detective (was it Full Moon?) and many many more.
Trip to memory lane heh... 
Edit: totally forgot Dark Age of Camelot... have all the expansions, manuals, guides and even software tools and havent played it in years (best pvp game ever).