Wow thanks for the feedback. I could make the first level a tutorial where player learns all necessary keys and rules.
I liked all of your suggestions. Adding a captain, new enemy types and difficulty levels sounds very interesting.
Actually I made this game project to test how well deep learning works in turn based games. But I agree that this could end up being a fun and challenging game if further developed.
PS. I know Games workshop is very strict about using their IP and might cause some problems. But this is just a free hobby project and not meant to make me any capital gains.