It works natively in browser, and even has a fun gameboy view on mobile. It's 100% a recreation, in that it doesn't use any of the original game code, other than the image assets and sounds. You can move around with the arrow keys, Spacebar is Start, and Enter is A.

It's MIT licensed, so feel free to fork it and do whatever you like

Contributions are very welcome, there's still lots of work to go until it's a full recreation of the game, so if anyone wants to help add content please feel free! Currently it supports up to Mt Moon.