Wear virtual reality 3D glasses, to see as a 3D image. Flag starts new game. Take turns. Use left grid: On your turn, click mouse to place on left grid (right grid copies left, but displaces for 3D effect). (In 3D tic tac toe, you try to get 3 in a row either within a grid or between grids, e.g. 3 in center position of each grid)
The grid is at slightly different angles for left and right eye, which merge into one with VR glasses. You could cross eyes to merge left and right images, if you don't have VR glasses. Left sprite follows mouse. Right sprite parallels left. The grid is turned a bit making it jump out of screen, a 3D effect.
