One of the interesting problems of Virtual Reality is that while the virtual world appears spatially continuous with the player, nothing in the virtual world can exert any force on the player or limit their movement.
Overcoming this problem, and creating an interactive world that reacts in a physically believable manner, and encouraging the player to play in a way that is congruent with the game world, is a challenge we've set for ourselves. We'd like to share a few insights that we have gained through tackling this challenge.