Some of the things that I have done so far:
-Scrolling background with repeating tiles
-Scrolling islands on background, with instances. Instances jump randomly back to the top once their y coordinates go below the game level, creating an illusion of new, unexplored lands.
-Player plane programmed to work with arrow keys. Testing where the x and y variables of the plane allows or denies movement based on current position (so the plane does not fly off screen.
-Instances of player and enemy bullets to generate at their origin, with a constant speed,
-Instances of enemy plane with collision Actions with player_bullet, and player_plane.
-Setting of score, player health, and lives with Actions to end the game when no more lives, and to blow up plane when health reaches 0.
-Implementation of sequence PNG images.
Once I finish this tutorial and maybe add some more features that I come up with, my plan is to recreate all the art assets. After that I will program them the same way so that I have an original game with my art and my programming.