Gameplay is interesting. I'm not good at this type of games so it`s hard for me to say how difficult it is.
It's hard to close the game. I'm not sure how I did it (I pressed Esc on story screen, but game stopped only after starting the game).
Somehow I didn't realized Spacebar is used for restart, but that's not that big of a deal.
Also it's hard to read text (story is on distracting background, and in-game text is too small to notice).