This cart demonstrates how to create particle systems. It is heavily commented so you can pull apart how this is being achieved.
Notes: The basic idea is that you create a table to hold all of the particles and then every frame you go through that table, updating and drawing each particle in that table. How you update and draw each particle is up to you. The secret to a good particle system is having enough variables for each particle so that there is good variety in the particles as they are created.
Save this file to your PICO-8 carts folder. Then load it by typing
load particles in the command line mode of PICO-8.