Really fun, and a cool idea!
I ran into an issue that might be a bug (besides the freezing bug you mention): when I got to the HQ mission, it seemed to just go on forever? Eventually I had such a massive horde of guys that any hero that dared to show his face got utterly annihilated immediately. Was I supposed to do something else there?
Also, a lot of the times the heroes in normal battles (and in the HQ one) would run off the side of the screen and my dudes would just run off the screen with them, and come back a bit later with blood on their hands. I.e. it feels like the area they could move in was bigger than the area I could see. I tried making it fullscreen, but it just put the small window into a large black box and didn't fix the issue.
But all that is just bugginess; the gameplay loop was fun and seems solid. More unit types and stuff would help make this game more variable and interesting over the long term, but obviously there was limited time! I also enjoyed the traits the heroes had to give them strengths and weaknesses. Very cool.