Paint with a USB mouse is a ready-made Basys 3 FPGA game written in Verilog. It uses PS/2 mouse on the USB port. Play it free right in your browser - nothing to install, no FPGA board needed.
How to play
Move the mouse over the screen: the left button paints, the right button clears. The switches choose the colour.
What it uses
Verilog · PS/2 mouse on the USB port
The code: download the Verilog project (.zip) — read it, change it, and run your version with the free PC program.