Here's a sketch that draws and rotates text wherever the mouse is clicked - its colour depends on it's position. Any position left or above the red line produces red text. Any position between the red and blue lines produces blue text. Any position between the blue and green line produces green text.
Pressing 1 creates a fadeout effect
Pressing 2 changes colours based on mouse position
Pressing 3 allows you to alter dot size with . and ,
Pressing r reverses the direction and draws a funky line - the other parameters can be engaged or disengaged while in reverse