Serious games in 3D virtual environments are becoming a popular tool for professional training activities as well as for rehabilitation. Navigation in 3D is recognized as one of the activity which is more dificult to master in this environments. In particular, elder users, less familiar with 3D games often do not know how to walk through these environments. They get puzzled without having been able to address the real purpose of the game. In this paper, we propose diferent enhancement methods to make navigation in 3D easier, and we describe the design and implementation of an automatic navigation mode, usable when navigation is needed to reach objects in the 3D world but is not a goal of the game by itself. We compare the results of an evaluation test of these di erent methods. We conclude that, for non-usual gamers, automatic navigation is the faster and preferred mode, whereas gamers prefer to control navigation themselves. For non-automatic navigation, the performance is better when the cursor is xed in the view center point during locomotion. On the contrary, for still positions, a free cursor is preferable. Finally, restriction of the pitch angle in a solid angle that encompasses the objects related to the task is better than a free pitch angle rotation for still positions. During locomotion, fixing the pitch angle at the horizontal level enhances the navigation.