wait someone cared!!!!! does the resolution feel off?
Well development goes (something) like this:
1) Create a core mechanic [moving paddle, shooting bullets at enemies, dodging enemies]
2) Polish core mechanic [paddle width and speed, enemy speed, bullet speed, explosion radius?]
3) Create core loop [score goes up as enemies are destroyed, score goes down when enemies get through. Speed increases with score. Game over when player hit or score is zero]
4) Polish core loop [Game speed increase rate, scoring system possibly based on enemy type, how forgiving of player mistakes]
5) Variations [different types of enemies, enemy formations and movement patterns, player powerups]
It's still at step #1 as shooting doesn't do anything. You could decide if shooting is even part of the mechanic, if it is, make it do something and go to step #2. If it's dropped it becomes a top-down endless runner and you go to step #2.
Good luck.