After a few viewer requests, we decided to do a Sixty Symbols video about the new game Portal 2.
It's a game with a lot of science content.
Physicist Professor Phil Moriarty agreed to buy the game and play it - then give his verdict.
Fellow Professor Ed Copeland (a particle physicist and cosmologist) hadn't played the game, but agreed to chip in because he knew a bit about wormholes!
As you can see from the video, I made a few cuts (and made a few jokes about it at Phil's expense). So it was only fair I also upload some of the extra footage.
Here's more from Phil.
And more from Ed.