Hello.
I was wondering if the gog version of Shadow Warrior 2 can MP/COOP with the steam version of the same game?
I know there are some games that you cant do this.
Is SW2 one of them?
Or can you play this gog version with the steam version?
Seems 'Friends' might be through steam, and you wouldnt be able to add a 'friend'?
Just an assumption.
But, we are trying to buy a friend a copy of the game, and we have 2 that have it therough steam right now, but the big steam sale is over, and here is gog with a great sale on the game, but it HAS to be compatible with the steam version for us to get it for him through gog.
Thanks

TLDR: Yes, crossplay is supported, via open server (that anyone can join, max 4 players). No, you can't invite friends from the opposing service (GOG/Steam) to a friends-only game.

Long version:
SW2 supports crossplay between any Steam/Gog version of the game. The issue is the friend lists, which are not synced in any way between Gog and Steam.

You can either play an open game, which anyone can join using any client, including your friends, after they find the game in the main server list. Problem is, in my experience, there is no way to set a password, so unless you have a group of exactly 4 friends, anyone can still join the game after your friends are connected.

You can create a friends-only game, but then you can only invite your friends in the service you are using (Gog, Steam), because they need to be informed of the "Galaxy Lobby ID" (that an invite contains).

If you're willing to go the extra mile, and desperate for a friends-only game between the two services, you can try this. This requires for the host to be running on GOG, because Steam invites are not as easy to find with Wireshark.