Croteams' shooter game Serious Sam 4 will be getting a stand-alone expansion in January titled Serious Sam: Siberian Mayhem, the development studio has announced.

Serious Sam: Siberian Mayhem is a new stand-alone expansion to the world of the classic FPS series. Join the fight against Notorious Mental on a journey through the wild lands of Russia, and find your way through this lost chapter of Sam Stone's adventures.

The game was designed and developed by Serious Sam modders, joined together under the banner of Timelock Studio. The team worked closely with development studio Croteam, the developer of Serious Sam 4, to bring Siberian Mayhem to life.

The game features a new campaign that can be played both in singleplayer and co-op multiplayer. It is said to deliver a "hybrid experience ready to deliver explosive fun to fans of classics, and the latest installments to the series." Its bigger brother, Serious Sam 4, will not be required to play the game.

Serious Sam: Siberian Mayhem will release on January 25 for PC.