Thunder Shield Challenge is the second Challenge Act of City Escape Act 1 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the Dreamcast era and is playable only as Classic Sonic.
The player is given a monitor containing the Thunder Shield, which they need to use to get through the Challenge Act within the given time limit. Due to this, the Act layout caters to the shield's powers, with electric obstacles in the way and high areas that cannot be reached without the double jump. Upon completion of this act, the player can buy the Thunder Shield skill in the Skill Shop.