This is really cool! There are lots of cool ideas and some really satisfying puzzles/aha moments. I think games of this length run into the problem of just how linear puzzlescript can be, but the level select at least removes some of the friction there. But that's only because there are enough ideas and interactions here to sustain a larger, less linear game.
Anyway, I've now solved everything except Monorail (which feels like it might be beyond me!) and Glass Cases (which I can see how to solve, just not how to execute the solution for now)
Excited to see how it develops from here :)