Serious Games for Virtual Reality (SG-VR) is still a new subject that needs to be explored. Achieving the optimal fun and learning results depends on the application of the most suitable metrics. Virtual Reality environments offer great capabilities but at the same time make difficult to record User Experience (UX) to improve it. Moreover, the continuous evolution of Virtual Reality technologies and video game industry tendencies constantly change these metrics. This paper studies the Mechanics, Dynamics and Aesthetic (MDA) framework and User Experience metrics to develop new ones for SG-VR. These new parameters are focused on the intrinsic motivations the players need so they engage with the game. However, the development team budget must be taken into account, since it limits items and interactions but still have to aim to the learning goals. New VR metrics will be 1) UX features: chosen VR headsets, training interactions tutorials to learn control and interactive adaptions to avoid VR inconveniences; and 2) MDA features: exclusive VR aesthetical elements and its interactions.
