That makes sense. I understand concerns like that. It would be nice if we could just write a contract, one that states that I agree to use the source code only

That makes sense. I understand concerns like that. It would be nice if we could just write a contract, one that states that I agree to use the source code only for personal use and that I may not use the code for a commercial product, or that I may only redistribute modded binaries for free and not modded source code, or something along those lines. That way, I could do the thing I want with it, without them worrying about if I'm going to try and rip off their game immediately. It wouldn't be as liberal as making the code open-source under something like the GPL, which isn't convenient, but it could be something of a good compromise. Do you think that would sound agreeable? Do you (or does anyone else reading) know enough about software law to know if you can do something like that?