I got all the kittens plus one, resulting in "-1 Left." By using a static List of Kitten object, AllKittens, in your Kitten class and calling AllKittens.Add(this) in your Kitten Awake() function you'll be able to get AllKittens.Count to refresh your UI properly. So in Kitten.Collect() you could call AllKittens.Remove(this) and KittenCounter.SetCount(AllKittens.Count). This would make sure your kitten counter is always right and you never have to change any fields if you edit your level.
The AI was super aggressive and pushed me through several walls. Luckily running out of health didn't do anything. I really liked the cube particles of the bullet collision.
Don't take my criticism personally; I know I went on for a bit there. Your game is actually really fun! I just want to see you grow! :)