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I see from previous posts that online was only between GOG Galaxy clients, but that they may add crossplay with steam later.

It's been later now. Is there crossplay yet?
seconding this question! My friends have the Steam version, but if crossplay is working I'll get the GOG version for sure.
Post edited July 24, 2021 by kvltd00d
I have never seen any mention of crossplay ever coming to SOR4 and would be astounded if so.

Can you link something to verifying your claim?