https://larian.com/support/faqs/multiplayer-information_53Is there Cross Play?
This in the process of being implemented. Direct Connection is possible between platforms, but all players must be on the same version number in order for it to work. Once cross play is supported, there may be temporary version discrepancies between platforms with game updates or hotfixes, which would prevent cross play until the versions match again, but we will try to synchronize updates as much as possible.
As of Patch 7, Direct Connection works between Steam and GOG, but does not between Stadia and computers (PC/Mac).
