Plotz!

Plotz! is an exuberant and obscure early game from Soleau Software, who would go on to publish a ridiculous number of puzzle-type shareware games. This game is a one-player vs the computer game where the object is to change entire columns on the game board to black before your CPU opponent can change them to blue. Each turn you click on a blue square, and some squares around it change to black. It wasn't obvious to me how this works; it seems almost random? But I'm sure if you have patience you can figure it out.