Portal 2 gets co-op update

Valve has released an update over Steam for Portal 2 that allows co-op level creation and sharing.

This allows players to design and publish co-op levels in the game, which has seen over 170,000 single-player levels created since May.

The update also adds Quick Play for players to access top-rated maps more efficiently.

Portal 2 owners are being given a Steam voucher for 75% off the game that they can gift to friends.