This is the first puzzle platformer I've played in a LONG time that felt like a good organic mix of ACTUAL puzzles, ACTUAL platforming, and a concept that wasn't overly contrived.
The concept of "you can jump an extra time for every chicken you have" is intuitive and immediately understandable, and the way that each stacked chicken increases the size of your hitbox makes the game difficult in a way that feels logical and fair. The extra mechanics (such as the buttons or spiky chickens) add a bit of depth to the gameplay, but from a development standpoint what I like is that you don't use them to bloat the game with logic puzzles; virtually all of the logic required to beat the game deals with the same stacking logic that the core mechanics are built on.
The graphics and music are cute (and I don't want to take anything away from your collaborators) but the concept and execution really stand front and center.
I do have a few criticisms:
One, the main "level select" area is nice, but toward the end of the game it can be frustrating running around trying to locate the last few levels you need feathers from. Having a map (just for this area) would have been helpful for someone looking to get those last couple ones.
Two, the game can glitch a bit. If you fall a long distance while pressed against a wall, you fall through the floor. I noticed a chicken do this once or twice as well.
Three, the game's performance can get a bit shaky. Lowering the quality helps a lot with this.