This is the sequel to “Code a Poker Game with Arcade ECS.” You start from the exact scene that course ends on — a complete, single-machine Texas Hold'em table — and make it a four-player online game. You build a small room server that gives each browser a seat and one shared secret seed; generate a room code and a shareable link; open a WebRTC peer mesh where every browser is equal, with no host and no central server; and bridge that mesh onto the same EventBus the single-player game already runs on, so the existing match director needs no changes. Because the deal is seeded, every browser deals the same cards and no cards are sent over the network, and each player sees their own hand at the bottom of their own screen while all four agree on whose cards are whose. WebRTC is new to many web developers, so the mesh is built from the basics — offer, answer, ICE, DataChannels, and why you need a rendezvous server — and one full lesson covers how to test networking code with no network at all. The finished build is the real multiplayer scene from the library.