EDIT: I am now in college. I will have decided to forestall p...
GameMaker Server is a GameMaker extension which allows you to add online INIs, online achievements, online highscores or online multiplayer to your game, without having to host your own server.
There are 1,380 developers using GameMaker Server, and 7,392 accounts have been registered. GameMaker Server hosts 1,723 games, and 196,140 logins have been made on 49,168 different usernames.
To use GameMaker Server, you'll need GameMaker. GameMaker can be downloaded on the YoYoGames website. The following GameMaker versions are supported:
To use GameMaker Server, you'll need a GameMaker Server account, and you'll need to register as a developer. Every game has to be registered as well, before any of the online functions can be used.