There is a hidden supercode in all versions of the Hulk game.

In the new Hulk game for all next-gen consoles, there is a supercode that lets you play as the original grey Hulk.

The code is apparently in one of the very first in-game scenes, and if you input the code you will be able to play as the original Hulk, who was grey in the first issue of the Hulk comic, but changed to green in the second issue.

There are also many other hidden codes and characters in the game.