What I like: There's a nice menu, decent graphics for starter game, the controls are smooth and responsive for the most part, and the premise is idea is simple enough. I like the introduction of the levers and switches and trap doors and things as the game progresses. For a game intended for 2 players, I played is solo, and that actually gave it sufficient challenge to make much more fun than if I was playing with 2 people.
What I think has room for improvement.
BUG ON MOVEMENT - When i'm flying/jumping, or sometimes even walking, I often get stuck against invisible walls that I cannot get passed, I'm not even seeing graphically where these might be from, they are super annoying and really take away from the game play.
BUG ON LEVEL COMPLETE - There's a major glitch in Co-Op where, if i Every single time if I sit on the wait screen for the next level up for more than 3 seconds, it crashes and gives me a game over, and I have to replay the level. If I click the "SKIP" button fast enough, it'll force start the next level. This glitch is consistent and reproducible across all levels. This is compounded by the screen size issue.
WINDOW SIZE - I'm playing with a native resolution of 1920x1080, and the game doesn't fit in my browser window, it's clearly designed for full screen, but it needs to be able to scale down to fit in into a frame, particularly since there isn't a full-screen option, and I honestly wouldn't use it. As-is I have to either give up my timer, or give up the top 10% of the screen, which is normally where the round ends.
LEVELS - clocking in 5 levels each about a minute long, it's a short game, but fun and challenging once you get around all the glitches. The 4th level was actually a little tricky playing solo, but the 5th level was just too easy. With all the dynamic pads and trapdoors you introduced, I was hoping for more or harder, not less and easier.
I'm rating this game based on what content I have access to, how long I played, how fun it was, and how much I want to come back and play more. Glitches aside, you've intended as a 2-player game, but I'm not sure it does well in that field. For me, I think it has a much higher skill requirement and more fun, as a single player game, simultaneously needing to coordinate my 2 separate chickens to escape! With more levels I would definitely come back and play more. But there are some hitbox and boundary issues and bugs that need to get fixed ASAP. I personally would drop the online/offline at the start screen, since it doesn't seem to do anything, and treat this as a single-player game that has a fun little Co-Op mode. For me, the base game is great.
With all the bugs fixed this is easily a 7/10 game, and with more levels and continuing on adding new things each level, even higher.
PS, I really appreciate how the chickens start off on 2 separate trails, and then are finally able to join up. I hope if you add more content, you'll keep this going, making them go separately and then back together, and so forth. However they end the previous level, is how the next one start. You have a fantastic premise here, I think there's a lot more you can do and improve it, and I look forward to it ^_^