Cross play is actually much easier than most assume, most look to consoles and Sony specifically, and assume this kind of implementation would be problematic, but, it's not. In the most basic of terms, multiplayer is accomplished by a player's computer sending information to a server which amounts to, "I am here, I am doing this." Because these updates are passed over a network, all that is required, is the game to be able to communicate as such. In fact, if you play on a 7 Days to Die, Ark, or Rust server, the server itself is very likely running on a Linux machine. The hard part, is the porting itself, because it's like changing the dialect of the language being used. Coffee Stain might not want to devote the time and effort required to port Satisfactory, or, they might already be writing the dedicated server for linux because it the easiest and most customizable OS to put a server on remotely.