Fun little shooting game! It felt very satisfying hitting the 1000 point targets at the back. I loved the artwork and voice acting in particular :D
Personally I'd consider removing the cooldown/delay between firing shots as it just felt like it got in the way of the fun. That said, if you did want to keep it maybe add a reloading sound effect to indicate when the player is able to shoot again? I think that'd help improve it.