Classic idea done well, great job! I really appreciate the small details, like the day/night cycle and the flavored game over text. And of course the art is fantastic and a really good fit for this game. I'm also always appreciative of people who used the "My Own Noise" diversifier :) [I think technically this is a one-button game too?]
For constructive criticism, I definitely agree with the comment below about being able to use additional control schemes rather than clicking. I'd also add that I wish the BAM cooldown was desynced from the barrel- at a certain point the red zookeepers were unstoppable because you couldn't throw and bam them in time (only one or the other) and that doesn't feel great when you're stuck in a losing situation