Code a mobile friendly game with LittleJS

Hey all! I hacked together a super simple game last weekend, which I thought lent itself to a tutorial.
So, I also wrote up a tutorial, which can be found here:
https://eoinmcg.github.io/little-ski/tutorial.html
and the game:
https://eoinmcg.github.io/little-ski

If anyone has the time and inclination to check out the tutorial, I'd really appreciate any feedback!
Thanks!

p.s. the github repo: https://github.com/eoinmcg/little-ski/