Hey there,
thanks for trying out my game and giving this feedback. It helps me a lot!
"Challenging" is exactly what I had in mind with this game but considering the feedback I receive it is probably a bit too challenging right now and not rewarding enough. I will make lots of balancing tweaks to make the game more fun to everone (not just the dev himself :D).
Still great to hear that you played it for a while!
Thank you!