This is really cool! The pixel art is great and you've nailed the NES feel especially with the difficulty lol. I'm sure the person you made it for will be super flattered!

My only real complaint is that it's too small. I was able to enlarge it by making some html tweaks so you might be able to play around with the Newgrounds embed dimensions? Something like 720x576 might be a good fit.

I found 'Ctrl' for run and 'J' for jump ruled out using arrow keys, so you have to use WASD. But that's a tiny nitpick, and on a controller it works great!

Super impressive work, keep it up! :)

Absolute banger! The yt vid was amazing too!