Fun design, great soundtrack, good sfx, great intro.
There's a few things to critique (which is likely due to you giving us so much game to play)
First is that, toward the end of the game it becomes apparent that the best overall strat is to sit in the corner and fire all around the room until you stop hearing the damage sounds from the cats. It does become funny that when you get the ping pong, that your own fire can be your biggest threat but it can be played around pretty easily.
Second is that, because of how easily you can do that toward the end of the game, the maps become absolutely massive with so many cats to kill. It starts to not feel fun having to kill every single cat on the map. You made so many levels, but I think maybe you could've made less levels and spent more time fine tuning/adding new mechanics/enemies. There are some cool things introduced but after you get the plants it becomes pretty samey.
Third is just a slight sfx thing, but the shooting sound and glass sounds for the potions need a bit of low-pass filtering/compression/transient shaping. They're pretty harsh. I like the sfx a lot overall, just needs mixing.
I'm pretty miffed, I got to level 16 or so and then accidentally clicked out of the game. I wanted to see the end boss but I don't think I can play through all those levels again.
Good game, super impressed with the amount of stuff in there.