Thanks a lot for your kind words.
The 4 hit limit is indeed problematic, but i couldn't find a way to increase the length of the game without making it too hard or too uninteresting. I'll think about it.
I should also point out the fact that while the canvas height diminish, the perceived speed of fragments and bullets stay the same, so the time it take for them to hit is actually reduced.
I'm glad you had some fun.