i thought the things in the bottom left corner were lives, or how many times you can accidentally shoot your assigned number. but it's just ammo, which i feel you should mention in your "how to" section.
i do like that you have limited ammo because that forces you to strategically decide which numbers to shoot. it prevents the game from just being "shoot the numbers you're not assigned." but that does require you to count the other numbers, which might be tricky since they're always moving (or maybe that's part of the challenge).
i don't know if this is just a web build issue or something, but your assigned number goes into the bottom right corner *too* much and goes out of the screen when the level starts. regardless i think there should be a reminder of what your assigned number is because sometimes i just forget instantly lol.
overall it's got a lot of potential. the cover image reminds me of those cgi animations of robots demonstrating sorting algorithms :)