Hey, thank you for playing and recording! Even witout audio I can clearly see your thinking process, this helps a lot.
In the video everything seems fine with the villager spawner so it might
Yes the upgrade system needs to be modified completely.
I also think knights could need a little more health.
It was intentional that you cannot place units on fields immediately after another died but idk if it might feel frustrating. Just wanted to make sure if an enemy unit kills one of yours it steps at least one field forward.
Thank you really glad to hear that!