This mahjong route on Ocean Arcade Game is based on the open source project kobalab/Majiang. The original project supports online rooms, but that feature needs a separate server package and authentication flow.
On this site, the standalone parts are the ones that are live: local table play, autoplay, scoring drills, hand study, and replay tools.
If you specifically want multiplayer later, we can wire up the separate mahjong server as a second phase.