Wanted to make a twist on vampire survivor too, but I wasn't sure how to make that work. Gotta say, what you guys managed to achieve within 2 days is surprisingly very polished, to the point where it feels like a full game that could potentially compete with vampire survivor itself if actually made endless!
Some improvements I feel could make the core gameplay loop better are, firstly, maybe having at least the more basic pigeons be auto-cast off cooldown each time. After a while, my hand started to hurt from spamming the pigeon button. I think it could also be interesting to be able to choose where certain birds will spawn at, especially the jacks since they fly in a straight line. I realized halfway through my playthrough that if I am lucky, I could actually use the jacks to move the "Player" towards steven, or a bunch of pigeons, so being able to choose where jacks spawn from could add more strategic depth.
Other than that, I really love this game, especially the upgrade that adds more birds to each time I press a button, and I would definitely appreciate an endless mode!