Valve's first-person puzzler Portal 2 has received a significant update today. For months, players on PC and Mac have been able to create their own puzzles through the "Perpetual Testing Initiative." However, these creations have had to be solitary affairs. No more! Starting today, Portal 2 players will be able to design and play co-op maps.

In addition to adding co-op, the UGC mode has been enhanced with a new "Quick Play" feature that creates an automatically generated playlist of top-rated maps to play through. That should help appease fans that actually want to test maps perpetually. Current owners of Portal 2 will find a 75% off coupon awaiting them in Steam, so that they can wrangle in a new player to join in co-op puzzle antics.