It was a fun chess variant, good job! Does this chess variant have a name?
My first game against Alice was a draw, it ended up king vs. king, but the game doesn't recognize that situation as a draw. So I had to reload.
I won the second game against Alice and I could beat Carl Brok on my first try. However, he never used his "undo" special ability. The game progressed really gradually though, maybe that's why.
Also thanks for making it open-source, I will check out how the AI works sometime!