Have you ever wanted to try paintballing? What about in a large urban area like a city centre? Well, it may surprise you to learn that the local constabulary don't really like people running around with guns.. loaded with paint or anything else. So, how about using a camera phone instead?

How do you use a phone instead of a paintball marker, I hear you cry. Well... we can use a special type of barcode called a QR (Quick Response) code (that square-shaped logo in the corner of the page). Here's how it works:

• Install a QR reader on your mobile. I recommend UpCode (point your phone's browser to www.upcode.fi)
• Everyone playing the game wears a tshirt or other item of clothing with a special QR code on the back (and possibly on the front, too)
• Everyone playing the game stays within a pre-arranged area - the 'warzone'.
• Someone 'shoots' your barcode with their phone, and you get a text message saying you've been shot, and you're out of the game - although you should try to shoot them first.
• Once shot, you proceed to a pre-arranged area outwith the warzone and have a drink with your fellow casualties.

We'll be staging the first game of QRBall in Glasgow in the next few weeks. Interested? Email qrball@googlemail.com

Oh, and if you've downloaded a QR reader, try it out on this code: