Hello everyone! The "central" repository right now is the games section in the forum.
@crait and @JO3RI also have repositories for their uploaders now that are compatible with the new .arduboy file format.
Because of the nature of open source we let users host their own code however they like.
In the future we are working on making an online repository and web-flashing tool so that you can come to the website, plug in your Arduboy, and then download a new game with one click. Just now getting our head above the water setting up the new server this year to begin to handle that.
We envision the website to have a new section, an Arduboy Arcade that would exist along side the community forum where users download games directly form there. The problem with this, is that games will have to be submitted for approval. Right now, because people host their own games, you're free to upload whatever you like into the forum and we plan to keep it that way.
With the new system, when we host the repository and the code on our servers we will have to make sure there aren't any intellectual property issues or otherwise.
So stay tuned for that!