That’s first-person shooter tower defence, of course. Sanctum, a UDK-powered project that we reported on some time ago, is now fully evolved up into a commercial project and has a pre-order-based beta going up on Steam. Want to know a bit more? Well, there’s a detailed video below, which explains how you set up your game in a classic tower-defence building phase before taking on the creeps with both the tower network you’ve created, and your own weapons. Looks interesting, and the art style is neat, too. The full game hits on April 15th.