Amazing Puzzle game with an interesting story. The whole time your questioning what's going on\ why you only have some robot talking to you.

The main gameplay gimmick is being able to place portals on any (allowed) surface. So the main way to solve puzzle is to figure out the best portal placements. Of course the game adds physic elements to add more depth.

It's pretty much dirt cheap nowadays and it's really short. Like if you get a somewhat decent handle on the game you could beat it in a day.