Shatter (PC)

Usually I'm not a big fan of these Arkanoid / Breakout clones, but Shatter is pretty darn fun.  I think the game's music helps a lot with this.

Dungeon Defenders Screenshots (PC)

Dungeon Defenders is a very action-oriented tower defense game.  It's become quite popular since its release, and has a ton of DLC.  Personally not my cup of tea, though.  I much prefer Orcs Must Die! and Sanctum. ^_^