  One of the most striking quantum phenomena is superposition, where one
particle simultaneously inhabits different states. Most methods to verify
coherent superposition are indirect, in that they require the distinct states
to be recombined. Here, we adapt an XOR game, in which separated parties
measure different parts of a superposed particle, and use it to verify
superpositions with \textit{local measurements} and a second independent
particle. We then turn this game into a resource-efficient verification scheme,
obtaining a confidence that the particle is superposed which approaches unity
exponentially fast. We demonstrate our scheme using a single photon, obtaining
a 99\% confidence that the particle is superposed with only 37 copies. Our work
shows the utility of XOR games to verify quantum resources, allowing us to
efficiently detect quantum superposition without reinterfering the superposed
states.
