If you've always wished that tower defense games played more like real-time strategy games like Command and Conquer then Anomaly Warzone Earth
might be just the game you're looking for. Called a "tower offense" game, it plays like a very simplified RTS. In it, instead of placing defenses, you're guiding an attacking force through winding streets while avoiding or destroying enemy defensive emplacements and, at the same time, building up and/or upgrading your squad.
This video, straight from the developer's mouth, details the six-mission Tactical Trials
pack exclusive to the Xbox 360 version that comes out on April 6th.