Super Mario 128 was the quintessential tech demo. Shown at Nintendo's Space World in 2000 to put the then-unreleased Gamecube through its paces, it featured -- you guessed it -- 128 Mario models goofing off on-screen.
According to Player's Choice Games, the Gamecube laughed its way through the presentation, never exceeding 25 per cent of the console's capabilities (represented by the green bar in the image). Miyamoto even cranked up the effects and the hardware still sat there, periodically checking its watch.
How did it influence Super Mario Galaxy? Not much, actually. At GDC 2007, Miyamoto stated that its greatest impact was on the game's level design; it contributed more to the original Pikmin than anything else. It's been said the Marios ran about on a sphere -- in actual fact it was a deformable disc (an impressive feat for the time).
This is just one long lost game covered by E-mpire below. Hit the link for a roundup of four others, including Peter Molyneux’s B.C. and EA's Black 2.
Image: Player's Choice Games