How to Play

• Drag your finger/mouse to move the racquet
• Lift your finger/mouse to swing
• Press 2 fingers/buttons to switch

You can only hit the ball when some part is in our 3-dimensional world (i.e., where the 4th coordinate is 0).

A "hint" image will show where the first 3 coordinates are located in 3D space (i.e., ball's "projection" to ℝ³).