League of Legends (PC) - its Dota, with a lot of the annoying things ripped out, like denying. Free to play. Has a community that shows that though.
Terraria (PC) - People say its 2D MineCraft. If that deters you, slap yourself in the face. It has a focus more on exploration rather than building. Has Magic, special weapons, is a blast to play with friends (youll need some sort of program like Hamachi to run it in Multiplayer though), and boss fights. Very fun and engaging.
Castle Crashers (X360) - A fantastic side scroller action game, presented in 2.5D. Visuals are gorgeous, gameplay is fun, and the game is a laugh and a half. Easily surpasses a lot of games that charge the full $60 price tag.
Aside from those three, check out the XBL Arcade. This service doesnt get nearly enough credit as it should, as it is easily a great source of a lot of great games. Are you a fan of Sonic before he went spiraling out of control? They got you covered. Games like Limbo, Braid, DeathSpank, Section 8 Prejudice (or whatever its called). And plenty more. Check it out sometime.
As you already mentioned Scott Pilgrim, I dont need to. That game was freaking amazing. The soundtrack alone was well worth it.
