I'm glad you enjoyed it!
I would have liked to add some audio, and I actually had a soundtrack I wanted to use but decided against adding a potentially web incompatible library for it because 3am... I might also go back and adjust the instructions. The level select UI in particular is sort of terrible since I rushed to complete it on the last day without any UI framework whatsoever, and only then could I even design the levels. The person I showed it to the day after I submitted it didn't even realize they were supposed to click "new solution" to start. I probably should have just used "next" and "previous" buttons within the solution editor, a "switch solution" button/interface, and a "switch world" button to go between A, B, and custom levels.
I am in fact a Factorio fan. The mechanics are based on a power/crafting system in a Minecraft datapack I made a while ago and never got around to sharing with anyone (maybe this is confirmation that I should consider it... 3d also brings something extra to the splitter puzzles).
Speaking of Factorio, and totally off topic, I really dislike the way it handles pressing both left and right at the same time. No matter which one was pressed first, you go right. In Minecraft, you don't move at all (reasonable but irksome to me). In Celeste and by inspiration this game, the most recent input is used.