Modern demand-side management techniques are an integral part of the envisioned smart grid paradigm. They require an active involvement of the consumer for an optimization of the grid's efficiency and a better utilization of renewable energy sources. This applies especially in so called demand dispatch systems, where consumers are required to proactively communicate their flexibilities. However, a monetary compensation may not sufficiently motivate the individual consumer for a sustainable participation in such a program. The proposed approach uses a motivational framework leveraging the novel area of gamification, which applies well-known game mechanics, such as points and leaderboards, to engage customers in the system. This is accomplished by embedding a special scoring system and social competition aspects into a stimulating user interface for the definition and management of flexible energy demand. In a first user study, the system showed a high user acceptance and the potential to engage consumers in participation.