What's the use of anything? Seriously, you're on HackerNews where all sorts of one-off projects with no purpose except to exist get displayed and you're asking

What's the use of anything? Seriously, you're on HackerNews where all sorts of one-off projects with no purpose except to exist get displayed and you're asking what the use of an NES emulator is? Maybe the author wanted to learn about emulation, or found it a challenge to do in Go. Does it matter? If you don't enjoy it, move on.