In my experience, most of the pain boils down to synchronization of state between participants. This is also your principal vector for cheating.
If you are willing and able to make a very extreme sacrifice regarding client-server architecture, it is feasible to consolidate all state to 1 synchronous domain while serving an arbitrary number of participants.
The sacrifice is basically to build your game as a native take on the Google Stadia model. I.e. inputs are raw player events, output is a low latency A/V stream back to player.
Keep in mind you don't have to always serve an x264 stream to all clients. Depending on your objectives and type of game, you can serve an intermediate view model that instructs the client on how to draw its view using local assets and resources (textures, models, gpus, etc). This would be more like how Blazor server-side model operates.
If you are willing and able to make a very extreme sacrifice regarding client-server architecture, it is feasible to consolidate all state to 1 synchronous domain while serving an arbitrary number of participants.
The sacrifice is basically to build your game as a native take on the Google Stadia model. I.e. inputs are raw player events, output is a low latency A/V stream back to player.
Keep in mind you don't have to always serve an x264 stream to all clients. Depending on your objectives and type of game, you can serve an intermediate view model that instructs the client on how to draw its view using local assets and resources (textures, models, gpus, etc). This would be more like how Blazor server-side model operates.