Yeah, it was mostly the last level of your game that was beyond my ability to track everything in my head. I was just about to break out the pencil and paper or give up when I finally figured out the strategy. The others were challenging but simple enough for me not to get too frustrated. But I also usually do pretty well at puzzle games. Maybe you could have an "easy" mode where you have a key to switch planes without actually moving. Or maybe you can do that, but it counts as a move so your score is worse?
As for Filament, yeah. Philippe did most of the level design, and he kept making levels that were fun for us but very difficult for new players. We have a farm, so Saturday and Sunday are usually work days for me and I didn't have anywhere near as much time as he did. I tried to make a few easier levels but mostly spent my time adding some bits of UI and visual feedback (things like the switching-between-levels code), which seemed more important at the time. Thanks for playing!