It’s been six long years since players escaped the Aperture Science complex in Portal 2, but a new game will thrust test subjects back into the bleak world later this month. In partnership with developer ClockStone Software, Bridge Constructor: Portal will challenge players to solve puzzles by utilizing mechanics from the Valve classic and Bridge Constructor.

The combination is weird—and unexpected—but bridge building games have become immensely popular over the past few years. Adding in the mechanics from Portal will add an entirely new element to the experience. The introductory video spells out what the game will be like.

“Bridge Constructor Portal will blend the laws of structural engineering and technology straight from Aperture Laboratories into an exciting new game experience, all under the demanding gaze of GLaDOS,” ClockStone Software explained.

So, it’s not a Portal game in the traditional sense. Then again, Portal isn’t a traditional game. If you’ve never experienced the joy and silliness of Portal, you’re missing out.

If you can’t wait for GLaDOS to boss you around, you’ll be able to play Bridge Constructor: Portal when it launches for PC, Mac, Linux, and mobile on December 20. The game will also launch for Switch, PlayStation 4 and Xbox One early next year.