Click on the screen to spawn the particles. Press Space to Show/Hide the Variables. You can change the force slider to add gravity. You can change the force direction to choose between dowards or centered gravity. The Collision Friction is how much energy is lost in every collision 1 means no loss. and 0.5 mean half of the energy is lost.
Since the particles are made in pen and pen particles don't have collisions you have to calculate their distances to each other to find out if they collide. I would suggest you use TurboWarp with it you are able to spawn a max of 250 particles.
