A lot of people hit this site while looking for hashiwokakero puzzles, also sometimes called bridges. I thought that I might include a weekly feature dedicated to hashiwokakero puzzles, but I wanted to do them a little differently. In a standard puzzle, there is a field of circles with numbers inside of them. Look at this example from wikipedia:

The circles here are islands and must be connected with bridges so that any island may be reached by any other island by crossing a series of bridges. As always, there are rules to follow. Paraphrased from wikipedia:

• Bridges must begin and end at distinct islands, travelling a straight line in between.
• Bridges must not cross any other bridges or islands.
• Bridges may only run orthogonally.
• At most two bridges connect a pair of islands.
• The number of bridges connected to each island must match the number on that island.

If you need a better idea of what this looks like, see the solution to the puzzle above here.

A good puzzle variation, I’ve found, involves giving the solver less information and more to figure out on his or her own. So I wanted to see what I could take away from the puzzle and still have it be soluble. In some cases, the numbers on individual islands can be taken away and you can still solve the puzzle. But I wanted to take all of the numbers away. So I did. I did a one-for-one replacement of all of the numbers with random symbols. So, at first, you don’t know how many bridges there are on a given island, but you know that it has the same number of bridges as a few other islands. I decided to call my puzzle “Lost Bridges”, with the idea being that these bridges were built by a lost civilization who mapped them using numbers different from our own. Here’s an example of one suce puzzle I made up last night:

Now, I was working on this late last night and I goofed. The puzzle above has two valid solutions. In some ways this might be good, because if you’re really having a hard time visualizing what I’m talking about here, you can look at the first solution and then challenge yourself to come up with the second. And of course, there will be another puzzle next week.

Here’s a pdf of the puzzle and a second solution.