This cart is a simple example of how to add projectiles to your game.
Notes: The basic idea is that you will keep a list of projectiles and every time the player fires, you add a projectile to the list. Then every time the game updates, you move each projectile and then see if anything needs to happen now that the projectile is in its new position. For example, if the projectile is off the screen, remove, or if it collided with an enemy, do something to the enemy, and remove the projectile.
Save this file to your PICO-8 carts folder. Then load it by typing
load projectiles in the command line mode of PICO-8.