Valve recommends you sit down for this announcement, though you might also want to jump into the air and yell in excitement. If you really like playing Portal 2 co-op, that is (and who doesn't?).

The game's "Perpetual Testing Initiative" level creation mode will from now on allow you to create levels for co-op play, which wasn't previously possible.

They're also giving all existing owners of Portal 2 a coupon to get a second copy at $5, perfect for gifting to a friend for the selfish purpose of getting yourself a new co-op partner.

Finally, they've added a Quick Play mode to Perpetual Testing that creates a never-ending playlist of quality community-made levels. Perfect for the Portal addict in us all.

Have you created any sick Portal 2 levels yet? Experienced any great user-created content? Tell us in the comments or on Twitter.

[via reddit]