KNOT SNAKE

The snake may cross itself, but only as knotwork: every crossing must alternate over and under along its whole length.

• Steer with arrows / WASD, or swipe. Space starts, pauses and restarts.
• Cross only where both strands run straight and meet at right angles. The head must pass straight through a crossing.
• Following the snake from tail to head, crossings must go over, under, over, under, so each crossing needs its two visits to be an odd count apart.