And the link I pointed at also just punts on sound, for another example of a corner that you can cut.

I actually whacked a paragraph about how said emulator will not be the fastest emulator and it won't be a perfect emulator, but you'll certainly have some running games, and for that all the things I said will still be true. Making an emulator that exactly matches the console is hard, but making an emulator that more-or-less runs a game isn't that hard.