Bridge Constructor, the physics-based game where you're tasked with building bridges for cars and trucks, is being mashed up with Portal, the physics-based game where you use Portals to solve puzzles.
Both games are excellent at spelling out their main gameplay hook right in the title, so it's no surprise Bridge Constructor Portal lets you construct bridges and use portals.
Bridge Constructor Portal combines "the laws of structural engineering and technology straight from Aperture Laboratories" to create a standalone game. Among the Aperture technology is GladOS, who holds you under her "demanding gaze," according to the press release.
If you have a PC, you can start playing as early as December 20, and it also lands on mobile devices the same day. Console versions are planned and are scheduled to release "in early 2018."