I've also made my own implementation of CHIP-8 emulator. I was surprised that it only took me a few hours to got it working. I reserved a week for the project.

One thing interesting about making emulator is that, it's all-or-nothing. You can't tell if your implementation's working until you finish it. For my case, I did end up having a few minor bugs, which I promptly fixed and got the whole thing working correctly.

Maybe I should try implementing extensions next, when I've got the time for that. :)