Sanctum is a first-person shooter tower defense video game, developed by indie developer Coffee Stain Studios. Set in a beautiful science fiction world, you take the role of Skye, an elite soldier sent out to protect her hometown, Elysion One, from hordes of mysterious alien creatures.

The gameplay in Sanctum can be divided into the building phase and the extermination phase. In the building phase, the players can build and upgrade the eight different towers and the three weapons available. In the extermination phase, a wave of various creatures will try to reach the core, and the task of the player is to prevent them from doing so.