Ask HN: Non-compete: how do I prove when I started a project?

I have a project I've been working on for about a year in my personal time (weekends, nights, etc) when not at work. It's basically a game. I was planning to launch this on the web at some point in the coming few months, and later on in the app store/android market if possible. So, the thing is, I just received a job offer from a large tech company and I'd like to accept. They will ask me to sign a non-compete (it's legal where they are). But the problem is that, unlike my previous company, this company is in many different lines of business, including games. So there is overlap there. I have been reading up on non-competes and it looks like they are non-enforcable unless the company can demonstrate that confidential information/trade secrets was actually stolen and used to help the competitor in question. So the thing is, most of the code for this project is already written. But if the game became popular and they came after me, how would I prove that? It's not open source so I can't point to a github commit history or anything like that. Do courts look at modification dates/times on files? I realize this probably paranoid, I doubt this company is going to come after me for my hobby iphone app or whatever. However I'm just wondering if anyone has any insight into what I should do in this situation. (also, I won't actually be working in the games division itself, if that makes any difference). Thanks HN.