Difficulty: fairly easy
This is great. I put a lot of effort into polishing it. I even set it aside for a while because I wasn’t happy with it, then came back and fixed it.
It’s fairly long, but doesn’t have any particularly tricky parts. Pretty atmospheric, I hope. Not all of the 1-ups are hidden, and not all of the hidden details are 1-ups.
I don’t even want to say anything more about it; I feel like I’ll ruin it. Just play it.