Wow, getting over 60 is amazing. Glad you achieved that score.
Thanks for the criticism, I'll take more care of those in the future. As for the third point, there are some ways to let the player when to shoot (or not shoot). One is by click to shoot, which is bad as the player needs to shoot a lot and ends up spamming mindlessly. Another is by pressing a key to "hold" the bullet, but it gets pretty complicated for this simple game. And so I ended up shooting at a certain time interval and thus requires them to worry more about their position and movement. I think by limiting the player on when to shoot, the player has to strategize and think more.
Anyway, thanks for the feedback, those are very valuable as I don't have someone (and more time) to test my game :( Thanks for playing!