Body coherence in curved-space virtual reality games

Virtual-reality simulations of curved space are most effective and fun when presented as a game (for example, curved-space billiards), so the user not only has something to see in space, but also do there. However, such encounter geometrical problem: they must track player's hands well her head, effects holonomy would quickly lead violations "body coherence". That is, what player sees with eyes disagree she feels hands. This article presents solution body coherence problem, several other questions that arise interactive VR (radians vs. meters, visualization projection transformation, native-inhabitant view tourist view, mental models space).