I think the most fun I ever had was wc3 custom games (dota and td's) and diablo 2. Diablo 3 was awesome for about 3 days.... then the most disappointed I have ever been with a game in my life, I heard just recently they added pvp.... are you kidding me? Do they even know what end game content is? It's not making your character glow colors.....

Anyways since I nearly abandoned windows (photoshop is the only thing keeping me from removing it completely), steam for linux has kept me entertained. I also bought a humble indie bundle with torchlight in it which I heard was a flop.... blows diablo 3 away, I love it, all it is also missing is pvp. There are also rumors of dota 2 being ported to linux soon... we shall see.