So, is it required that you start with an existing project? It seems to me that the only requirement explicitly listed is that it needs to be playable in a browser.
> Take an existing game or game jam entry on GitHub, fork it and do something awesome with it.
Consider the edge cases:
What if you can't fork it because you've already forked it 5 months ago (but made 0 commits on your fork)? This is probably okay, right? If not, you could delete your existing fork and fork again.
What if you can't fork it because you have an unrelated repo with the exact same name already? This is also okay, right?
What if you can't fork it because it's your own repo and you don't need to fork it? This is not okay? Or is it okay? No clear answer.
There are times where it helps to have explicit rules/conditions.
If you really don't want to fork someone else's existing repo, want to participate, but can't violate rules, you could always start a project on your account, do a ton of work on it, then start an organization, and have that organization fork your own repo. But honestly, I'm pretty sure github cares more that you wind up with an interesting and fun game at the end of the day rather than you following to the letter about what to fork and not fork.
> Take an existing game or game jam entry on GitHub, fork it and do something awesome with it.
> Take a look at the following resources to see if there's one you'd be intersted in forking....
> Once you've found a game repository, fork it...
> Make sure your code is pushed to the default branch of your forked repository...
And, on the submission form, talking about your Readme file:
> Mention the Game Off, what changes you made, who was on your team, what technologies you used, throw in a screenshot, etc.
I dunno, all that seems pretty explicit to me.