I found this game when I was looking for a game that I would be into that I could also play with my kids.
Combine a first-person style game with puzzles, a great story and a sense of humor and you have Portal 2. I highly recommend it.
Here's the Steam description:
Portal 2 draws from the award-winning formula of innovative gameplay, story, and music that earned the original Portal over 70 industry accolades and created a cult following.
The single-player portion of Portal 2 introduces a cast of dynamic new characters, a host of fresh puzzle elements, and a much larger set of devious test chambers. Players will explore never-before-seen areas of the Aperture Science Labs and be reunited with GLaDOS, the occasionally murderous computer companion who guided them through the original game.