Thanks for the answer; it turns out I already knew about BeepBox (and also use sfxr). :) I have been looking around for music tools, I have put my hands on some (such as Linux MultiMedia Studio (LMMS) and GXSCC) and still have to see if I can manage to get something out of them!
Please do tell me if this bigger project sees the light of day sometime, even a simple demonstration. This made me curious! :)
Your game is one of those I have to come back to, to try to complete it… Maybe trying today, I am on a roll of processing former comments and games lying in my (mental and written) stack! X)