One of the moodier trailers shown at the Humble Games Showcase today was for Cataclismo, a new base building tower defense RTS from Digital Sun, developer of The Mageseeker: A League of Legends Story. 

Cataclismo is a game about building fortresses, “brick-by-brick,” in a dark fantasy world where a deadly mist has enveloped the landscape. In the trailer, the camera moves slowly through the game’s murky world, showing us swarms of ghostly white creatures in the midst of attacking a towering fort defended by medieval archers. 

It’s only a small glimpse of the game, but an intriguing one, and it really sets the mood of desperate survivors in a castle under siege by unspeakable horrors.

“A foul swarm threatens your efforts every night. Deploy skillful crossbowmen, blazing artillery, and brutal traps to fend off the monstrosities that rush your walls,” reads the game’s page on Steam. “Even if you survive the night, the Mist endures, and the Horrors will return. Gather and manage stockpiles to prepare for what’s to come, and research new technologies in an RTS economy that will see you scouring the map for every mineral deposit and battered crate of salvage you can find.”

While constructing a castle and fending of nightly attacks with warriors and traps sounds fun, there’s also a bonus for people who just want to build. Cataclismo will feature a creative mode where you can build freely “without worrying about your creations being destroyed by Horrors.”

No release date, or even release year, for Cataclismo has been announced yet, but in the meantime I can point you to the game’s Steam store page.