In some applications of wireless sensor networks, requirements such as energy efficiency, real-time, and reliable delivery need to be considered. In this paper, we propose a novel routing algorithm for wireless sensor networks. It provides real-time, reliable delivery of a packet, while considering energy awareness. In the proposed algorithm, a node estimates the energy cost, delay and reliability of a path to the sink node, based only on information from neighboring nodes. Then, it calculates the probability of selecting a path, using the estimates. When packet forwarding is required, it randomly selects the next node. A path with lower energy cost is likely to be selected, because the probability is inversely proportional to the energy cost to the sink node. To achieve real-time delivery, only paths that may deliver a packet in time are selected. To achieve reliability, it may send a redundant packet via an alternate path, but only if it is a source of a packet. Experimental results show that the proposed algorithm is suitable for providing energy efficient, real-time, reliable communications.