I really love the gameplay you designed and the models you used! The game has great replayability with the research tree and the different difficulty levels, especially for a game jam game!
The only thing I didn't find clear in the first round I played, was that the defense buildings were unlocked from the beginning, and you didn’t have to unlock them with cards like the other buildings. Because of this, I didn’t check the defense tab at the start and ended up playing for a long time without a shield in my first round. It was my own mistake, I know! I initially thought it was a small inconsistency, but if you considered this and have a specific reason for providing the defense buildings from the start, then never mind my comment!
But still, I loveeeee your game!