Knossos Games - If/Then City Blocks

For a long time I have wanted to make a puzzle based on the structure of the If - Then - Else statement. A lot of people, including many of my students, have a difficult time understanding just what the structure of an If - Then - Else statement implies. So I can both exploit that misunderstanding to make the puzzle difficult, while at the same time hopefully educate some people about what it means. While in college I tried a few variations, but was never quite pleased with the results. I don't remember how I came up with the notion of navigating city blocks from an overhead, map-like perspective, but it turned out to be the perfect match for the If - Then - Else structure.

This type of puzzle was the first of many that I started making in 2002 that required new methods of charting a problem space. Instead of simply drawing out a puzzle with the solution in mind, I needed to turn the entire puzzle-making process on its head. Let me explain what I mean by that. When I started making the first If/Then City Block puzzle, I had a large (approximately ten block by ten block) physical space for the problem, and had an intended solution path through the space. But coming up with the appropriate (challenging yet sufficient) clues that would eliminate all but the solution path turned out to be a nightmare.

Instead of continuing along that route, trying to find the perfect clues (which may not have even existed, given so many possibilities), I decided to start making tiny physical spaces and explore those. The first two examples I made can now be found on the index page as examples for this group of puzzles. In making the examples, I was able to get my bearings, so to speak, on how these types of puzzles might behave - how the statements and the space could interact with one another.

In making each puzzle, I would first choose a physical layout and the number of intersections that I wanted the solution to pass through. Then I would chart every possible way to connect the start to the finish passing through that number of intersections. I'd make up a chart that listed what happened at each intersection (left, right, or straight), in order, for each possible solution path. Finally, I would compare the structure of the paths, and look for differences at certain intersections. An example would be if all the paths went straight or to the right at the third intersection, except for one that turned left. From the chart, I could then write clues that would eliminate all possible paths but one. Because I now had a choice between many possible solutions, I made multiple sets of If - Then - Else statements for each physical problem space.

This method of finding all the possible solutions, then picking one of them to be the actual solution, was quite atypical to my puzzle making process. But this allowed me to make a type of puzzle that really wouldn't have been possible to make otherwise (i.e., the way I'd normally do things). I'm now using this technique more and more to create challenging puzzles with very "open" physical problem spaces.