Very fun, I could've played for 20 more levels of this.
I like that the one-screen sections are split into levels according to theme, and I also like that the sections are a bit more involved than in some other one-screen hacks.
The music ports aren't the cleanest, but they do give the hack it's own unique flavour, big kudos for doing that. There's some cheese here and there, and some rooms do feel like they're rehashing a previous room, but nothing egregious.
What does the number that appears on the bottom corner of the overworld mean? it changed from 9 to 39 after completing the first level and stayed there until I beat the game.
It's the life counter. Due to the deadline I set myself there was no time to fix it... you can't lose any lifes, but gain a bunch in the room with the infinite rex of the first level, that's why it changed to 39