There are Secret Levels and Expert Levels hidden in the game.
Shooting Orange Boxes, Targets, and 1 ups while on instruction screens add more points and ultimately more coins to your total.
There are 40 normal levels of Astro Barrier.
There are 10 secret levels and 9 expert levels
Pressing "1", "2", or "3" before clicking "Start" will start you at a later level. For example, pressing "1" will start you at level 10.
Shots are not reset between level transitions, which means if you can manage to shoot on a level transition (either by using a blaster or by making so in a tutorial screen), you can make your shot last through to the next level.
There was a bug during the Holiday Party 2019 which made the game unavailable to play. This was fixed on December 21, 2019.