No, you're not seeing things! Some of your fave computer characters came to life and took to the streets of London.
Well actually, it was a huge crowd of gaming fans who dressed up like their heroes to try to break the record for the largest number of people dressed up as computer characters.
Sonic the Hedgehog was on hand to help make the record-breaking mission a success.
This multitude of Marios look happy to be taking part!
Could this really be the largest group of people dressed as computer characters ever?
Well, this lot certainly hope so, and they'll be appearing in the Guinness World Record Gamers Edition 2009.