About Matrix Matrix is an open protocol for decentralised, secure communications.
Matrix Manifesto We believe:
People should have full control over their own communication. People should not be locked into centralised communication silos, but instead be free to pick who they choose to host their communication without limiting who they can reach. The ability to converse securely and privately is a basic human right. Communication should be available to everyone as a free and open, unencumbered, standard and global network.
There are open chat protocols, like XMPP. The issue is corporations either don’t use them, or use them to enshittificate (that’s what happened to XMPP, even. As for open GUI protocols, which is needed for the second part of your message, same issue: there’s open protocols and open toolkits all over the place, but the corps that produce consoles and games won’t use them (or, when they do, they’ll still lock them behind an “ecosystem”).
tl;dr: choose better (more open) games, and you can have p much all the chat you want.