Steam and Non Steam versions.

[Rovert]

Does anyone know if both the steam version and the non steam version are compatable with each other for co-op play?

[Dynamole]

There's no non steam version. It's a steamworks game.

[Ceejay]

Non steam = pirate. Even if you buy the physical copy, it registers itself on steam, and still uses steam.

[Happy Larry]

Yea but that was not the answer he was asked for... yes you can play together with a program like tunngle.
Or just download both of you the pirated version of the game and play it.

[Rovert]

Thanks for the answers, if it is a steamworks game, (I wasn't 100% on this and was only checking information a friend had given me), then it answers my question prefectly. Not looking to go down the pirated root at all so my friend will have to folk out the dosh if they want to coop.