My DS9 is currently on his 3rd version of a game he invented called Draw wars. He draws all this weapons and charaters that have points and then they battle. The battle is done by taking turns drawing the objects and then some body loses. Well,
Boy, do I have a playing partner for him! My DS7 has a similar game, but less dependent on good drawing and not always dependent on another participant--he has "dot battles" in which he chooses two to three colors and draws a few actual weapons and "troops", but mostly just...dots. Dots congregated in specific ways so as to outflank or overwhelm the other enemy dots. It has become a daily activity, often covering 2-3 sheets of paper and always described in great narrative detail. I try to "get it", but the truth is I have no clue what on earth he's talking about during much of his excited explanation.

He and DD have their own version of Calvin Ball too. I am glad that *I* don't have to play it--and equally glad that they have so much fun with it!