How do I add a file to a game that's already up?

I updated Usuru and wanted to submit it, but I only found the option to upload a new game.

1. Find your game in the game vault.
2. Go to the "Edit" button you find at the top left of your game.
3. Once there, you will notice "Game Type". It says "This is important if you are uploading a file. It will overwrite the current file." Make sure to select which one you're trying to overwrite (the demo or the full game).
4. Browse for the game file that you want to upload.
5. Submit.

No possible way to have both full games avaliable?

Only taking the most recent version of both a demo and the full game.

Even when logged in as Gitaroo, I can't find this button.

This is because the function relies on you being the one (actually, it's linked to your SSA) who uploaded the game. It was an issue I knew was bound to come up, since I am likely the one who uploaded many of the games. It's fixable, though.

Can you tell me what you were trying to do, so I can do it for you in the meantime?

Jut curious if this is being worked on, since I have Usuru I'd like to update.

Yeah, you can update it at any time.