Thanks for playing and detailed comment!
Thanks for an advice! I've already added (in the local repo) some intro levels. One of them is the level you just suggested me. Some of them on my piece of paper because I haven't added doors yet...
I plan to add at least trampolines and locked doors that could be open by key. I don't want to add them too early because I have tendency to forget about "things" that could be explored more...
About moving obstacles... It is a little problem in a puzzle level design you shouldn't mix puzzles with actions. The GDC talk in which you can find the explanation (starts from 25:06). I need to test some variations of this....
About gravity. I think I won't add it but everything is possible. I have a demo of future game that have gravity mechanic. It appears mostly in the end but give this game a try it also have non standard mechanic...