You are reading my mind ^^, I've start working on difficulty levels after your (and mike) comment and I planned a highscore menu.
I think I'll follow your advice and add a score reminder on the replay prompt.
For the difficulty, I think 1.0.0 level (5s) will be considered as HARD, NORMAL will be something like 7,5s and EASY 10s.
You can expect these features by the end of the week, I'll ping you ;)