As far as I know the Gatwick fleet only have the normal entertainment system in economy.
It is about 8 film channels (1 or 2 childrens films), some TV channels showing various TV shows (e.g. scrubs) and also about 12 audio channels but no video game system.

As I've said before we had a system coming back in April with the Super Nintendo games system but I think that was a 'loaner' from Heathrow.

Brizzle.