Defense Grid: Containment is a recently released expansion for the award-winning indie PC game Defense Grid: The Awakening. Defense Grid: The Awakening just happens to be a kick-ass tower defense game with a variety of game play modes and a heavy emphasis on strategy. The expansion adds 8 new levels and has already provided me with many hours of new game-play.
The story continues and this time takes the fight to the enemy. After you get past the very challenging first level you head through the portal to attack the alien home world. Once there, you start over with just the basics and quickly re-acquire your technology while making some new friends in the process.
In addition to story mode each new level has a variety of challenge modes. My favorite challenge mode so far is probably Grinder - where you try to hold out against 100 waves of the enemy. The DLC also adds some additional Steam achievements and leaderboards - making it fun to see how you compare to your friends.
I'm not going to lie - the expansion can be challenging and you will have to replay levels multiple times to determine the correct paths and placements of your towers - but I think this DLC is totally worth it. It's a great new addition to an already fantastic game.