Now you’re thinking with . . .

Christmas is a time for play, so let’s talk about a game. If you haven’t played the video game Portal, then I suggest that you stop reading this article and go and play it.

Welcome back. Did you play Portal 2 as well? If not, go and play that one as well: it’s even better.

If you didn’t take my advice, then you’ve missed out on a great experience. (Maybe you should go and try it - we’ll wait.) I believe that the Portal games are examples of just how good video gaming can be: intriguing, playful, thoughtful and challenging, with a sparse but engaging story.

In the games, you are a subject in a lab, and you have one tool to pass a series of strange and dangerous tests: a portal gun. When fired, this gun creates a hole on a surface, and when fired again, it creates a hole on another surface. If you jump through one hole, you come out of the other - it’s a portal! The games are an exercise in creativity on top of this simple premise, by both the developers and the players.