A play system, comprising: one or more toys comprising one or more electrically conductive parts, the one or more conductive parts defining a spatial pattern, the one or more toys having a physical configuration that is modifiable by a user, the spatial pattern being dependent on the physical configuration of the one or more toys, the one or more toys including a first toy; a magnetic field generating device arranged to generate a magnetic field for inducing an eddy current in one or more of the electrically conductive parts; a sensor configured to detect the induced eddy current; and a data processor; wherein the first toy and at least one of the magnetic field generating device and the sensor are movable relative to each other; wherein the sensor is configured to detect the induced eddy current during relative movement between the first toy and at least one of the magnetic field generating device and the sensor, and wherein the data processor is configured to: receive sensor data from the sensor, the sensor data being indicative of the eddy current detected during relative movement between the first toy and at least one of the magnetic field generating device and the sensor, detect the spatial pattern of the electrically conductive parts based at least in part on the received sensor data, determine the physical configuration of the one or more toys based on the detected spatial pattern.