What _why describes is half the problem. (Maybe a bit more than half.) In the Good Old Days, you could take your Spectrum/Amiga/BBCmicro/C64/whatever, and (1) write a program that (2) did something comparable to the games you could buy. (Less polished, sure, but not a million miles off.) Nowadays, #1 is harder because there's no programming language bundled with the system, because it doesn't drop you into a REPL whe…
I'm pretty sure I could write Guitar Hero in Python. (Oh wait, someone already did! http://fretsonfire.sourceforge.net/)