The paper aims to provide an energy efficient routing algorithm for Wireless Sensor Networks (WSNs). Clustering is a technique widely adopted in WSNs. It divides the network into clusters and the cluster heads are responsible for forwarding the aggregated data to the sink. There are many algorithms for forwarding the data to the sink. In this paper, a Game theory based Energy efficient Routing Algorithm (GERA) is proposed. As a clustering algorithm GERA adopts game theory and set a utility function based on the benefit and energy consumption of the node. Cluster heads are selected based on the utility function of the node iteratively. The cluster formation is done based on the cost function of the node in the network. Also an intra-cluster and multi-hop inter-cluster routing algorithms are designed and the simulation results shows that cluster heads are evenly distributed. The proposed routing algorithm consumes less energy than other existing algorithms such as Low Energy Adaptive Clustering Hierarchy (LEACH) and Density-based Energy-efficient Game-theoretic Routing Algorithm (DEGRA). Also the network lifetime is largely prolonged.