An interesting add-on for the Nintendo DS is this lovely potentiometer by Taito, somewhat reminiscent from paddle controller. Using a geared potentiometer actuation mechanism, the user experience is quite basic with brick-games such as Arkanoid. Rotating that sole button is intriguing and quite smooth. Of course some folks nailed it down more thoroughly and manage to control Mario Kart DS. Surely something to think about tangentially to this.