Hawken: An enjoyable lore, fun mechanics and fun mechs. Good amount of dakka.
AirMech: Interesting idea, although boring in the long run. Decent dakka.
Loadout: You get to create your own amount of dakka. Schweet. Boring in the long run.
Planetary Annihilation: An RTS with planets and lots and lots of dakka. Heavy for pc.
Planetside 2: The pure size, I mean it is so big! And I like it big. (pun intended)
Warhammer 40.000 Dawn Of War: Amazing singleplayer, amazing battles. Can run on toasters.
Warhammer 40.000 Dawn Of War Dark Crusade Titanium Wars mod: Ups the size of the normal DOW, more units, bigger camera, and one hell of a slaughter.
Warhammer 40.000 Dawn Of War II: Badarse singleplayer, and hole lot of carnage.
Warhammer 40.000 Dawn Of War II Chaos Rising: Even better singleplayer, and hard on even the easiest difficulties. (ULKAIR!!!)
Warhammer 40.000 Dawn Of War II: Retribution: Singleplayer is mostly fun due to the army you can have, and orks. ("I`ll set me gitfinda to panzie boss!")
Warhammer 40.000 Space Marine: You make Kratos look like a p*ssy in the singleplayer, and oh dear lord the customizer in multiplayer...~!
And the last, but by no means the worst:
Lego Universe: Enjoyable enemies (except Nexus Prime, damned gorillas), customizing almost everything, potential to build gorgeous LEGO structures, and friendly mods. RIP.