In wireless sensor networks (WSNs), the coverage problem usually accompanies the energy-saving issue, which ensures the fundamental functions are workable. Therefore, the sensor nodes must be deployed and survived in the target place for a long time, and sustain the trade-off between expected coverage and limited battery energy. The lesser sensor nodes are awake in an epoch, the longer network lifetime is achieved. It shows that the coverage problem must be solved based on the energy efficiency viewpoint. In this paper, we propose a game-based WSNs environment and solve the energy saving issue with the minimum number of competition players, which implies the most suitable duty-cycle for all sensor nodes. In the simulation results, the proposed approach achieves the lowest power consumption and longest network lifetime.