Educational games have been shown to provide support for children with learning disabilities to overcome their challenges. Gaming and feedback elements can benefit the learning process while keeping children engaged and help them to regain motivation for learning. We present the design of a mobile serious game for German dyslexic primary school children that incorporates gaming elements such as narrative, pedagogical agents, tutorials, feedback, and reward mechanisms. We derive our game design decisions and specify the rationales behind with special focus on the needs and demands of the target group. We evaluate the gaming elements based on the results of 63 children who played the game at home during a period of 9-10 weeks. Results indicate overall positive perception of the game elements. Children were immersed in the fantasy-themed world, liked the pedagogical agents, and indicated that the interactive tutorials gave an easy start into the game, and emphasized the special importance of praise.