While the user-friendly Perpetual Testing Initiative had produced 170,000 player-created single-player testing chambers for Portal 2, the tools weren't yet available for creating co-operative challenges; until today.

Valve has announced that the puzzle make now includes co-op test chamber support, with the latest update also introducing a new "Quick Play" function, that allows players easy access to the top-rated user-created maps.

In celebration, the developer has also awarded every Portal 2 owning Steam user with a 75% off coupon that can be given away to friends to purchase their very own discounted copy of the game and share the love. For more details, head over to the official site.