Gratuitous Space Battles

Developer: Positech Games

Released: November 2009

Gratuitous Space Battles is exactly what it sounds like. The developers said, you know what? Some people just want space battles without the burden of plot or drama or characterization. So here you go! GSB is a highly tactical 2D space combat sim with gazillions of options and a ton of complexity. It might look like an RTS, but due to the focus on setup it's more like tower defense.

Orcs Must Die!

Developer: Robot Entertainment
Publisher: Microsoft Studios
Released: October 2011

Orcs Must Die! is a quirky blend of tower defense and third person shooter. You play as an apprentice warmage defending portals (rifts) from the orc world to our world. Each stage takes place in a different castle protecting a different rift. The warmage must place traps, cast spells, and use all the weapons at his disposal to prevent the horde from reaching the rifts, while trying not to be overwhelmed by his overconfidence.