Pause game play, then enter the "Fortress of Solitude" options menu. Enter one of the following codes at this menu to activate the corresponding cheat function.
Press Up, Up, Down, Down, Left, Right, Left, Right, Y, X.
Press Left, Y, Right, X, Down, Y, Up, Down, X, Y, X.
Press Left, Up, Right, Down, Y, X, Y, Up, Right, X.
Unlimited city health:
Press Y, Right, Y, Right, Up, Left, Right, Y.