We decided to change the presentation of the 16th puzzle. Glowing spheres are placed at checkpoints along the way to emphasize the need to pass through them.
In the process of confirming this change, we realized that a different approach than the expected correct route was possible. The correct solution to this puzzle is to connect to the goal in one stroke. However, there is one part that can branch, and if you use this, you can take a route that is not a single stroke.
It took some time to verify, but it turned out that it was possible to connect to the goal using a branch route. This would reduce the difficulty of the puzzle, so we changed the shape of the branching parts, but it still reach the goal by a different route.
For this reason, we decided to modify the parts to prevent branching. With this modification, it is no longer possible to make all the parts glow (turn green) when the answer is correct, but it can’t be helped.