We developed this game for VR in a few months with the goal of simulating life as a pet hamster.
My job was to program the movements within the ball such that the acceleration would not lead to motion sickness. I successfully achieved this by syncing the rolling with the motion controllers 1-to-1. In addition, when the player goes outside the ball, the screen will fade to black. This will keep them "grounded" without clipping through walls and without experiencing vertigo.