Defense Grid: The Awakening - You Monster DLC

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

In this first full-story expansion to the award-winning Defense Grid, GLaDOS, the menacing AI from the awesome Portal franchise, guest stars and shakes up the Defense Grid world. Players will battle not only alien hordes, but the deviousness of GLaDOS as she tests the player’s skills and changes all of the rules that you have come to know. Can you protect the cores in spite of her intrusive testing?
Defense Grid: The Awakening is a unique spin on tower defense gameplay that will appeal to players of all skill levels. A horde of enemies is invading, and it's up to the player to stop them by strategically building fortification towers around their base. Beautiful environments, spectacular effects, and a dynamic, engaging soundtrack bring the world to life. The controls are intuitive and the gameplay is deep — the special attacks and properties of each tower work together to provide many ways to succeed.

Key features:

Defense Grid: You Monster adds:

8 new maps with an all new story.
35 challenge missions.
7 new achievements.
Over 15 hours of new gameplay.