Treasure Master is a video game released by American Softworks in 1991 for the Nintendo Entertainment System as part of a contest involving MTV.
After the game's release in late 1991, players had until noon EST on April 11, 1992 to practice beating the game. At this time, MTV revealed a secret password. By entering in this password and the game's serial number before beginning the game, players unlocked a secret sixth "Prize World" level. After this, players had until midnight to complete the entire game including the Prize World. This prompted the game to reveal a 24 character code. By calling in to a special hotline with this code, players had a chance at winning one of 36,252 prizes.
The password to play the full game is: 3HDJL9DNQV2WYTV4S91RXR86
Source: Wikipedia, "Treasure Master", available under the CC-BY-SA License.