As mobile phones become smarter and include a wider and more powerful array of sensory components, the opportunity to leverage those capabilities in contexts other than telephony grows. We have in particular identified those sensory capabilities as key components for modern user interfacesthatcan detect movement, actions and intentions to enrich human-computer interaction in a natural way. In this work, we present research around using smartphones as input controllers in the context of exertion videogames. We proposea conceptualframework thatidentifies thecoreelements of such interfaces, regardless of the underlying technological platforms, and provides a design pattern for their integration into existing videogames without having to change the game’s source code. We present a proof of concept implementation for the framework, with two smartphone input controllers, which using a soft button and accelerometer data, interface to a target-shooting exertion game played while exercisingonastationarybicycle.Wepresent findings froma user experience evaluation.