Minecraft (in particular their Creative mode) seems to be the closest software to a paint program, as far as artistic expression is concerned. I haven't seen an

Minecraft (in particular their Creative mode) seems to be the closest software to a paint program, as far as artistic expression is concerned. I haven't seen any other software where so many people have created their own worlds and objects in 3D, painstakingly, brick by brick, that can be explored and interacted with in first person. I even built a small city in the game myself several years ago, and would spend some nights just watching tv while strip mining in the game, in order to gather the raw materials to build with. No other game before or since has compelled me to do that. There's probably a market for a dedicated paint program where you are essentially placing different shapes and colored/textured 3d blocks on an invisible grid, with the focus on providing features for that, not making a game around it.