I started with an originally very simple concept (at first it involved a cannon, but ultimately it wasn't even necessary, so I removed it) and then the level got more complicated than I ever thought it would be.
There is one very difficult timing move in this level, which was needed to make the rest of the design work. Otherwise, things wouldn't work properly.
There are no "new" tricks in this level, but the solution is far less obvious than you may think at first...

So, maybe I should just start basing levels around existing concepts, and complexity will soon "build itself"... as it did here.
EDIT: So apparently I'm stupid and missed a more obvious unintended way through the level. After Marinus helpfully provided me a screen shot, I realized how to probably close it. If you've already downloaded the level, please download version "A". It has a blue shadow stinker in such a spot as to attempt to prevent this.