In 1983, Parker Brothers created several games for the Atari 2600, including The Incredible Hulk. Not much is known about the gameplay, save for a few screenshots released in magazine ads.
This was in the age of the infamous Video Game Crash, in which many developers never released games already made for the Atari 2600. Many of Parker Brother's games were thought to be lost, but then found later as prototypes. One of the only games never found was The Incredible Hulk. In 2001, a promo box was bought and scanned online, suggesting that the game's prototype might indeed exist somewhere.