Straightforward and well implemented. A great little jam game!
I think the weakest piece is the mid- to late-game pacing in that I was leveling up so fast that the ability popups began to feel obnoxious. While most of them felt good, I think the overall power curve could be flattened considerably in favor of fewer, less frequent, but more powerful choices. Near the end, with a wall of bats shielding my yeti horde, I think the game was all but done, but I still had to click through a bunch of power popups to be able to actually win which didn't feel great.
But aside from that, the core loop itself is satisfying. It takes a bit to ramp up but when you get going, those specialized choices start to feel more meaningful and it's nice to see your army slowly overwhelm the enemy.
It turns out that "reverse vampire survivors" was a popular choice, but I can see why. It's a good game with a clear path for development and the games are almost always fun to play. Well done!
Great job on your game. It's an huge achievement for 48 hours. Keep making games!