Things I liked:
- Bad Piggies + Learn to Fly? It's a very good concept.
- The music in this is excellent.
- The game feels very polished. The visuals are good, there's an animated opening cutscene, an interesting credits scene, and a well-executed main game system.
Things I didn't like:
- I have x1 chicken, but x0 of the other characters. I didn't even realize that I could use them until I read one of the other comments here. It's a small detail, but I feel that it bears mentioning.
- The "durability" is more of a suggestion than anything else. I didn't really need to do anything but buy progressively larger amounts of propulsion with pretty much no regard to overall structure or stability, meaning that the gameplay feels a bit linear. At the time of writing, I just realized I've never used a powerup--I've never needed to.
- Another small detail, but when the tutorial screen says "place one of these characters to start", I thought it actually wanted me to click the character and put it on the screen. Another small detail and skill issue, possibly derived from playing Project Situs before this, but again, I think it bears mentioning.
Regardless, good job!