I don't play games with much frequency, but I play on some combination of Steam Deck and a desktop running OpenSUSE Tumbleweed, a Linux distro.

Edits/Changes: Forgot to specify Tumbleweed.

Not sure, but does it meet the any legal definitions of a sandwich anywhere — as in it can be advertised or sold as a sandwich?

I'm not sure what my favourite is, but Screen Cheat, of which may be found on Steam, can be fun. The gimmick is that it is a local split-screen shooter in which it is practically required to look at others' screen to know where they are as everyone is invisible otherwise, aside from projectiles.

*alleged sandwich

You may want to check out the Matrix protocol and implementations. There exist bridges for IRC and other communication networks or protocols.

You likely can just interpret it however you like. I doubt the purpose of this exercise is to follow the prompt to the letter. But then, I am not the author of the prompt.