Here is one Wiggly Numberlink puzzle.
Here is one Numberlink puzzle.
This construction is easily generalized to show that clues suffice to force a unique solution on a by grid whenever . That the shorter side of a grid which can be forced with clues grows at least exponentially with is quite surprising – when I first started wondering about this, I expected linear growth with a slope of about 2 or 4. Is a shorter side larger than possible?