No. Claiming that Stellaris is cross-platform is misleading since Stellaris Multiplayer on consoles is locked to their own ecosystem (XBOX only with XBOX, PS only with PS). Stellaris is only cross-platform on open systems like PC or Mac, where third-party stores like Steam or GOG are available.
So, that was the management summary. When discussing if Stellaris can run Multiplayer games across multiple platforms, we must clarify what ” platform ” means.
Stellaris instead has cross-store multiplayer options. These allow Stellaris Multiplayer across PC, Mac, and Linux.
On the one hand, when we talk about consoles as platforms, no, Stellaris Multiplayer cannot be played across the great divide between, say, PC and XBOX or between XBOX and PS. In the true sense of the word, Stellaris is not really cross-platform.
Fact: Stellaris is not cross-platform between XBOX and PC
So Stellaris is not cross-platform even between XBOX and PC. This is a little strange to me since at least a PC and an XBOX are both based on Windows.
So I assume the issue with cross-connection to consoles is that these cannot run Steam or GOG, with the manufacturers controlling what software can be run. And blocking anything that could rival their stores on these consoles.
But cross-platform Stellaris Multiplayer games are a reality whenever we can use the Paradox game launcher included in Steam or GOG Galaxy. So if you and your friends are using any store launchers like Steam or GOG, you can play Multiplayer cross-platform even over a different OS.
Update in 2021 brings Cross-Store Multiplayer
In 2021 Paradox kind of acknowledged that their self-developed Multiplayer infrastructure (“PDXMP”) was not an optimal solution, and even cross-store was only possible by using a “Beta” launcher version in the Stellaris launcher. But finally, in August 2021, the Multiplayer infrastructure was moved to a proven, third-party provider called “Nakama.”
With this decision, Paradox enabled stable cross-store Multiplayer for all Steam or GOG users.
Fact: Using one of the launchers, you can play as a PC user on Steam with your friends on a Mac.
Starting a Cross-Store Multiplayer in Steam
To play cross-store Multiplayer, use the drop-down menu next to “PLAY” in the Paradox Stellaris Launcher.
Alternatively, you can start a cross-store session also under “game settings” in the launcher.
Or, if for some reason all these methods do not work, you can try by taking it one step further and – before you start the Stellaris Launcher in Steam, right-click on Stellaris in your library list -> General -> enter “-nakama” in the launch options.
Fact: Stellaris is not cross-platform between XBOX and PS4