This game just goes over the top with everything, I like that!

Where it all started, really, you have to play this at some point in your life!

Simply put, the best game I have ever played, it combines the great storytelling that Valve does with the mindbending portals now with gels, platforms and other puzzle elements.

I love how Valve has put more emotion into four robots, two humans you never really see and the main character (Chell) who never speaks than I have seen in any other AAA game or movie.
When you think something has gone unexplained, just look around and you will find it, for example, look at the name on one of the "Bring your daughter to work day" projects then listen carefully to what people say and a whole other story can be put together!

Anyway this review is getting long for a Steam recommendation so I'll leave you with this, story mode will take you around nine hours to complete, more if you sit around listening to all the dialog, look at the enviroment and piece together the back stories while co-op will take another good seven or eight hours, less if you have a good partner so there's great value here!