Fun game! I loved the upgrade cards between rounds, it felt really good to change my strategy around which cards I got.
I think a smaller map might help combat a bit of the aimless feeling I was getting, like I kind of felt like I was off in the middle of nowhere defending nothing, but there was something quite fun about making my own little army of towers that I then tried to lead enemies through.
I did run into a bug after I died, pressing "retry" didn't actually restart for me - I was hoping it was going to restart me at the wave I was on, but nothing happened.