Like people said, that you have a non-disclosure agreement has nothing to do with the GPL. My point was that no matter what other things you do with the softwar

Like people said, that you have a non-disclosure agreement has nothing to do with the GPL. My point was that no matter what other things you do with the software, including using it for a commercial game, you can also release it as GPL. Other gamedevs absolutely can use it. The only thing they can't do is include it in a shipping product. Light Table appears to be an IDE, and there is no problem using a GPL IDE for writing a commercial product any more than there is a problem compiling it with GCC.