I have some rules questions:

4. Games should have a clearly defined beginning and end.
Not sure what you mean by this? Lots of arcade games had no end, except for dying...

Or do you mean that death is a defined end?

6. Your game should be written specifically for the competition. You cannot submit a game that was started before the competition began. Anyone found to be breaking this rule could be subject to disqualification.
What if I had a game idea pre-competition, but I never actually wrote any code (I only had a concept screenshot)?

I assume I can use the idea as I never started the game?

cheers,
Paul