Quite fun to play! I just don't think i fully understand what I'm doing :) when the countdown start again - did I reach the next level? I would say try to guide the player a bit more.
You are right, I should have added a tutorial or something but I'll tell you instructions here;
Z - shoot
Space - go invincible for a little
1-8 - go to a specific level
Sorry for your inconveinence
No inconvenience at all, still enjoyed playing :)