Zen Studios, the group of flipper fanatics behind Star Wars Pinball and Pinball FX 2, unleashes its tower defense variant, CastleStorm, on Steam today. Available for $10, CastleStorm touts physics-based destruction alongside wave-based tower defense mechanics, owing its existence to "the fond childhood memory of building and destroying LEGO castles."

In addition to the Steam news, Zen Studios announces the first DLC pack for CastleStorm will be out Wednesday, July 31. Dubbed From Outcast to Savior, the DLC pack – the first of two planned supplemental offerings – will simultaneously launch on Steam and Xbox Live Arcade for 240 MS Points ($3) and add a new Royal Guard faction, maps, Hero, weapons, Skirmish and Survival levels, Achievements and 20 additional battles to wage war through. Happy warmongering!

Source: Steam & Joystiq