The wonderful indie studio 2D Boy has just announced that its game World of Goo is a year old. To celebrate, it's offering you the chance to buy it for whatever price you think the game is worth. So, it's a bit like Radiohead's In Rainbows album, but actually worth money.

Usually selling for $20, the promotion runs until the 19th October and applies to the downloadable Windows, Mac and Linux versions. World of Goo is also available on Steam, WiiWare and Mac Game Store to name a few others.

You can pay your own price for World of Goo by clicking here.