Say you are making a game where the pillars of doom are moving around at rapid pace. The intersect and collide, go through. The game master can create small pillar at his whim. So can you. The catch is the direction of the pillars can be either vertical or horizontal...
You can catch hold of any pillars and make it yours. The longer you can keep it with out any of the pillars touch your pillar, the higher your score will be. How can you see the pillars colliding, intersecting? Changing colors, that is the best medium to show change.
Objects need not be just shapes, it can be images too. Yep, rectangles are converted to images with simple call to image() function as shown below. That brings the power of P5.js when it comes to play.