We present ExpanStick, a novel thumbstick that augments video game interaction using the force that the user applies at the physical limit of the gamepad. Gamers frequently manipulate a thumbstick leaning on the limit, or physical boundary around it, either to apply maximum input or to secure physical support, which makes the contact force an easily accessible input channel. The ExpanStick preserves the form factor and usability of the thumbstick, while expanding its input space. We built the ExpanStick and inserted it in a commercial gamepad as a proof-of-concept prototype. Using the prototype, we conducted a design workshop with console gamers to design the ExpanStick game interaction. Through demonstration of the interactions, we found the early use experience with the ExpanStick is positive and well accepted by the game players.