Edit: so no interest. I thought free was pretty good, I normally get a 6 figure salary
The problem is not no interest.
The problem is "how long are you willing to stick around".
Typically a game could take 3 months - 12 months in making.
If you want to help out someone because you're free for the moment, that moment could be very radical according to your life and could last a week, a month? and then the project has to try pull in another dev and get him adapted to your flow of code... not to mention reading through your code (and in most cases not great commenting because who has time).