If you want to use SuperCollider as the audio engine of your video game, you would indeed need to comply with the GPL. At least if you want to use the C library (libscsynth). Alternatively, you could run scsynth as a separate process and communicate over OSC; this is a bit of a grey area.

However, most people use SuperCollider as a tool to create music; in this case the GPL does not apply.

> and no one is going to use it (it being Supercollider) in anything resembling a commercial product.

This is patently false.