Hi,
a nice Example.
But, why not use Gamelogic Server-Side?
For Hacking, Cheating etc.

turn each map into its own room in that room object have all the players in that map in a array in that array should be player objects when someone joins that map have it add it to array then send each players x / y cords to each player that should solve your new map issue I can do this in python but dunno how it'll work in js dunno how objects work

In the current implementation of the game, when a player navigates to a different map and then returns to the main map, the online player disappears from the first map. This issue seems to be related to how the game handles map changes and updates the onlinePlayers object.

Steps to reproduce:

1.Start the game with multiple players.
2. Navigate one player to a different map.
3. Return the same player back to the main map.

After doing so the player who has changer their map and then has returned to the main map won't be able to see the multiplayer player again but the online player can see the first player back on the main map

Expected behavior:

The online player should be visible on the main map after returning from a different map to all players on that map.

Actual behavior:

The online player disappears from the main map after returning from a different map.

As i could see, this game can be hosted on a server so that people can play it without going through that long installing process.
So would you please mind to host it on a server like heroku or something else similar... This will also be helpful for you because there can be many testers who would love trying this game out and can help you find bugs and even fix them...