Tis a big one.
Im not sure why, but so many problems hit me when i played this game. I've played a good majority of your games, and there all fairly well done, and this game is no different. But i feel compelled to shed some light on its many shortcomings. Not sure why i feel this way this time.
1. The controls. There very clunky and unresponsive. Im not 100% certain if its the design of the game, or simply lag. Because that is another issue. Lag. It runs very slow. But again, im not 100% sure if this is lag or the game design itself. Either way, its not a good thing. He does not react to my key presses in a short enough amount of time. It seems like there is to much time between the time when i press jump and the time that it actually takes him to jump. This also goes for ground stomping (especially frustrating), walking, and pretty the while game in general. Its a common issue with alot of your games, but i think your overlooking it to much. Maybe you need to sacrifice some of those nifty graphics for smoother gameplay, or maybe optimize the code to allow faster reactions.
2. Level design. Its a pretty big issue. There are some flaws in the overall design of this game and others of its nature that you guys have made. There are always separate paths leading to random platforms in the middle of nowhere. Sometimes, they are random and simply provide a few more egg things. Other times, they are essential to getting past the stage. This poses a problem. I do not feel the need to take every path, nor do i notice every path. This amounts to missing alot of these essential paths. This, leads me to a dead end. It takes me a few minutes to figure out that i cant go foreword any longer, and have to backtrack. Backtracking is a very bad thing. It simply isn't fun. Been there, done that. Also, it causes me to spend countless minutes figuring out how to continue, now knowing where to go. Ignorance on my part is hardly my fault. Its the game designers fault. The correct course of action should be clear, if not implied. Your puzzles really don't make any sense. Like in the little robot level, i need to turn a floating Gear to make a big wall of dirt blocking my path to fall down...it makes no sense. Puzzles are supposed to make sense. You use logic to figure them out. If the solution is completely illogical, then the puzzle is completely lost to random fucking around with everything i see. You need to streamline the levels.
3. I cannot shoot or throw while jumping. Im not sure why this was left out, but it would be nice to have.
4. Being a somewhat vertical platformer, the camera does not work especially well. Its hard to see what it is your jumping on. You need to have a balance between how far your zoomed out, fall and jump distance, how closely the camera follow the character. They need to work together to allow the player to see where he is jumping, what he is jumping on, and avoiding those leap of faiths where you simply don't know where your going to land.
5. The character needs to be stuck on the ground when going down a slope. Up the slope is fine, because he is constantly pushed up. But when the character is going down a steep slope, he just runs off, gravity takes over and brings him back down. What you basicly need to do is the same code you use to keep him above the ground, except reversed, so that he does not come off the ground when walking either.
6. Animation system needs to be more intuitive. EG: When I walk off an edge while walking, the walk animation should not keep playing. There should be a fall animation.
7. Getting hit is no fun. Does not feel like I got hurt in any way. Needs more impact.
8. Dying is not fun. My health depletes (after being hit a bunch of times and not noticing), and it simply goes to a menu screen. No death animation. Music. Nothing.
9. When I was the robot, the white bullet blended in with the background much to well. Often white on white. But of a design issue there.
Now more character space left for positives. But there there. Critical statements are more useful anyway.