The Defense Grid: Containment DLC adds 8 new levels to the game, comprising 4-5 challenges each. The levels feature a continuation of the storyline where the main game left off and also introduces a couple of new characters, which is pretty cool (though the voice acting leaves much to be desired). Although some of the new levels feature different types of environments, nothing has fundamentally changed about the core gameplay (same towers, same strategies, etc). And just to be clear - I'm not saying that's a bad thing. This is pretty much all I want or need out of a Defense Grid DLC. That said, I do have one slight disappointment, which is that these levels all seem particularly easy (or maybe I've just gotten better at the game... I dunno). Regardless, if you're like me and just find this game fun and relaxing to chill out with, then picking up this add-on is a no-brainer.