Is co-op online or only local („couch“)?

Only local couch co-op. Not even LAN support, though that is in line with the original console versions.

Hope this helps

Flynn

Yes it does, thanks!

I wish I could buy it on GOG but Steam has Remote play, which allows you to do co-op even in this game (seems you require xbox controllers or smth tho).
Steam Remote Play Together feature is great for these games, unfortunately GOG doesn't have anything similar yet, that I know of.

Yes, there is a way, we and my friend downloaded a program called "Parsec" wich its like a team viewer but compatible with controllers. t's really easy to manage, goodluck :)