Use WASD or arrow keys to move the pencil. 1,2,3, and 4 change how the pencil looks. 0 is to erase all. If the bottom of your pencil touches the 4 colors or erase it will do that. E is to put your pen down on paper and r is to pick it up. You can also adjust color, saturation, thickness, and brightness by moving the little dots on the variable blocks.
There are other games that are maybe similar but I don’t know one and came up with this by myself. Enjoy!