Also, I just found a bizarre glitch. It's hard to reproduce, but essentially, by maneuvering between two screens and the screen loading taking a certain amount of time, I'm able to collect things on the exact opposite side of the screen.
Drat. I'm aware of this problem, but I thought I had it beat. Key blocks gave me so much trouble because they destroy slowly. I'll see what I can do.
I recognize that being restricted to the same enemies as when KS was first released back in 2007 makes it very hard to create a level that feels fresh. KS+ has the ability to change the appearance of enemies, but not their behaviors. Although programmable/new enemies is a brilliant idea, it's beyond the scope of this project. One of Nifflas' concepts for Knytt Underground was to be able to combine movement, detection, and attack AI to create a large number of possible enemy behaviors. Since I didn't want to encroach on KU, I decided not to include programmable enemies in KS+.
Polana, I have often wanted those invisible shapes myself. However, I don't regard the ceiling to be a critical area for smooth collision. Also, you can make any invisible shape you want since they're actually visible, 1 degree of blue. You can include them into tilesets.