wow, thank you a lot for your detailed review, i really appreciate it!
for the art, i tried to adhere to the limitations of typical "16-bit" era systems with up to 32 colors on-screen at once and resolution limitations (so tiles/sprites are 16x16 and almost all of them use just 3 or 4 colors, background layers are monochrome, and the screen resolution is 320x240). which was perhaps a bit brutal of a self-imposed limitation in hindsight, but i'm glad it reads as cohesive and holds up reasonably well!
i agree that the game is a bit long. looking back, a few levels less for more varied and polished wall graphics and longer/more music tracks would have been a reasonable tradeoff.
yeah, the ball mechanics are a bit cursed. lerp feels much smoother and less janky (and interacts well with the parallax background scrolling and the cylinder spinning), but it gets annoying when you want to sway to collect a heap of gems or when you try to suddenly reverse course to dodge spikes, so i kinda combined both, for better or worse. could have made it configurable or context-aware, but i ran out of time with the "everything solo from scratch" thing going on and slept through most of the bugfix day lol.
in regards to gamemaker, i actually made the game using gamemaker 8 from 2009 originally for sentimental reasons, as that was one of the first game engines i used when i was 8 years old, and i thought it would be kinda poetic to make my first game jam game using it as well. i then imported it into gamemaker studio 1.4 and then finally into the latest lts 2026 version, dragging the code through almost 2 decades of breaking changes. things hit the fan and i had to manually correct the migrated/auto-converted spaghetti without indentations but i gotta admit it was lowkey a fun challenge :)