>This is commonly known as cheating

I agree, I don't like to bring in existing code. Once I saw a friend of mine do (very obviously), still the jury was so impressed that they awarded him $25k in advertising for his bootstrapped startup. That moment I wished I had done the same thing:)

I'm pretty sure you're talking about some game, not hackathons.

Most of those I attend are aimed at competing over what you can create in x hours. If you've spent a week beforehand building it to present then it is essentially cheating. So yes, it is really a game.

Surely, it's hard to draw the line, what if you've written a similar thing before? or spent weeks coding in your head before hand?