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A global game will share its state with the entire server; this means that only one game can be run on the server.
If you need to run more games, you would need to host it on another server.

If you want to host multiple games on the same server, check out instanced games.

Global games are mostly used by large server networks that can afford many servers.
If you are running a smaller server, instanced games may be a better choice for you.