It's like writing a raytracer or ray-casting engine, it's not particularly useful but it's pretty fun and it can learn quite a lot while doing it. In the case

It's like writing a raytracer or ray-casting engine, it's not particularly useful but it's pretty fun and it can learn quite a lot while doing it. In the case of emulators I suspect that many developers nowadays never went underneath the syscall layer (or even beyond the interpreter) so if they're interested to learn about how it all works deep down it can be a good challenge. Of course the GameBoy is archaic in most ways but it's a start.