Portal 2 has received a new update that is focused on co-op level creation and sharing, Valve has announced.

The update to "The Perpetual Testing Initiative" brings co-op level creation and publishing to the in-game puzzle maker, which has already seen over 170,000 single-player levels created since its release in May.

On top of co-op puzzle creation, the update also adds Quick Play, enabling players to quickly access the top-rated maps in a number of categories.

If you're concerned about not having a co-op partner, all Portal 2 owners are being given a Steam voucher for 75 per cent off that can be given to a friend.

Valve's puzzler is a work of genius, earning 10/10 in our Portal 2 review.