There have been experiments:
Some people loved four-player riff on Super Mario Bros. that Nintendo introduced in 2009's New Super Mario Bros. Wii. I didn't. It was too chaotic. The other players got in the way. Griefing each other was fun for a time, briefly.
Some enjoyed the four-player of LittleBigPlanet, which preceded the Mario one and certainly was a marvel for player creativity. But those jumping controls... I preferred to play the game solo and not worry about players leaving each other behind.
Next from the laboratory of four-player action gaming is Ratchet & Clank a series that has long mixed Mario-style platforming with a most ridiculous arsenal of guns. This October's Ratchet & Clank: All 4 One allows up to four people try to go through a Ratchet game together. Is that a constructive addition to the series? A dollop of chaos? Or, hopefully, the perfect balance of both?
At a Sony PlayStation showcase in New York City last week, I shot a video of four people playing the new Ratchet, to see how it's coming along. Take a look... (click the video up top!)