#25 - UKPA 2024 Puzzles
This year I was invited to create a full round for the UKPA Open 2024 tournament. For this competition I also tested most of the rounds, which contain many amazing puzzles! The instruction and puzzle booklets can all be found here.
Since I'm quite fond of making hybrids, I quickly had the idea of making some sort of puzzle circle with classic genres, and hybrids thereof. I knew I wanted a good mix of types of genres (number placement, shading, loop etc.), and after quite some thinking eventually came up with the rotation Snake, Pentominous, Castle Wall, Kurodoko, and Japanese Sums. Interestingly, I set over half of these puzzles on paper, something I barely used to do before.
At first I created 2 classic puzzles of each type and a total of 5 hybrids (so 15 puzzles in total), but after testing it quickly became clear that hybrids are often a lot more difficult to solve than you think. Hence, I decided to reduce it to only one classic of each genre. In total the round was worth 322 points with a time limit of 55 minutes.
Snake (24 points)
Snake puzzles are absolutely not my comfort zone and I never set one before. That's actually why I thought it would be a good idea to set some! Also, the general properties of Snake would be easy for hybrids, as I did not want to create hybrids that would get too complicated regarding the rulesets. The eventual puzzle was not as easy as I intended the Snake to be, and is also probably my least favorite of the set, but at least there is some 24 theming in there!
Rules
Shade some cells to form a 1 cell wide snake of unknown length, whose head and tail are given. The snake does not touch itself, not even diagonally. Numbers outside the grid indicate the number of cells in that row/column that are occupied by the snake.
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Snake/Pentominous (15 points)
This was one of the hybrids I struggled most with. I had several iterations of rulesets that I was not exactly happy with. Eventually the biggest issue was that I did not use the numbers outside the grid at first, but that led to bashy, trivial or non-unique puzzles. After initial tests I decided to incorporate the outside numbers, which made for a much more pleasant puzzle. At this stage I also wanted to make it an easy puzzle, as the set was already getting quite long to solve.
Rules
Snake rules: Shade some cells to form a 1 cell wide snake of unknown length, whose head and tail are not given. The snake does not touch itself, not even diagonally. Clues outside the grid indicate the number of shaded cells in that row/column. Additionally, the snake can be divided into pentominoes in such a way that each cell of the snake is part of exactly one pentomino, and no two pentominoes of the same shape (including rotations and reflections) exist within the snake. Letters inside the grid are on the snake. A cell with a letter must also be part of the pentomino associated with that letter.
Example
Puzzle
Pentominous (14 points)
Pentominous puzzles with black squares are not that common, but since I did not want the puzzle to be either trivial or too hard, I had to make a smaller grid than 10x10. I do like this puzzle for its size.
Rules
Divide the grid into pentominoes (five cell regions) so that no two pentominoes of the same shape (including rotations and reflections) share an edge. Black cells cannot be part of any pentomino shape. A cell with a letter in it must be part of the pentomino associated with that letter. Not all pentomino shapes need to be used.
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Pentominous/Castle Wall (27 points)
This was the easiest hybrid to come up with. I have once before set this type of hybrid, although that one is still unpublished. I really liked what this ruleset implicates, so I wanted to show more of it to the world. A bit unfortunate about the unnumbered clues in the middle of the grid, but still a decent puzzle.
Rules
Castle Wall rules: Draw a single closed loop through the grid. The loop travels horizontally and vertically and must not touch or cross itself. There are black and white clue cells in the grid. White clue cells must be inside the loop; black clue cells must be outside the loop. Numbers in clue cells indicate the total length of the loop segments in the direction of the arrow. Additionally, empty cells not used by the loop form pentominoes, such that no two pentominoes touch orthogonally, and no two pentominoes of the same shape (including rotations/reflections as the same) occur in the grid.
Example
Puzzle
Castle Wall (22 points)
I had already set two Castle Walls for the contest, but suddenly decided to give a 24 theme a go for the fun of it. I was so thrilled when this actually worked out that I had to include this one in the contest. It's nothing too difficult, but it has a bit of a knacky ending.
Rules
Draw a single closed loop through the grid. The loop travels horizontally and vertically and must not touch or cross itself. There are black and white clue cells in the grid. White clue cells must be inside the loop; black clue cells must be outside the loop. Numbers in clue cells indicate the total length of the loop segments in the direction of the arrow.
Castle Wall/Kurodoko (57 points)
This was probably the most unnatural hybrid to set. The rules interact in some interesting ways, but also have no interaction at all for some purposes, which is quite different from the other hybrids. Getting the Kurodoko unique was the biggest challenge of them all, which in the end led to some larger clues than I would have liked. I am happy that quite some interesting steps were still maintained. Something I did not think about upfront was that this would have to be solved on paper, for which notation between the puzzle types could be quite tricky. I do hope it was not too annoying in the end for most people.
Rules
Castle Wall rules: Draw a single closed loop through the grid. The loop travels horizontally and vertically and must not touch or cross itself. There are black and white clue cells in the grid. White clue cells must be inside the loop; black clue cells must be outside the loop. Numbers in clue cells indicate the total length of the loop segments in the direction of the arrow. Kurodoko rules: Shade some cells. No numbered cell may be shaded. A number indicates how many cells can be seen (including the cell itself) from that cell horizontally or vertically up to the edge of the grid or a shaded cell (whichever is reached first). No two shaded cells may share an edge. All the white cells must form a single orthogonally connected area. Additionally, Castle Wall clues act as walls for the Kurodoko, meaning that Kurodoko clues can only see up to a Castle Wall clue, and unshaded cells cannot connect through a Castle Wall clue. Shaded cells can touch a black clue cell.
Example
Puzzle
Kurodoko (26 points)
Packed clues always acquire some trippy features, but I mostly wanted to make the solving experience of the Kurodoko quite different from how the hybrids with Kurodoko would solve. Perhaps not the most enjoyable puzzle ever, but a good change of logic during the round I would say.
Rules
Shade some cells. No numbered cell may be shaded. A number indicates how many cells can be seen (including the cell itself) from that cell horizontally or vertically up to the edge of the grid or a shaded cell (whichever is reached first). No two shaded cells may share an edge. All the white cells must form a single orthogonally connected area.
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Kurodoko/Japanese Sums (58 points)
This hybrid had quite interesting features, some of which I tried to incorporate in the solve. Even though it tends to be quite heavy on the Kurodoko at first, after which the Japanese Sums part is still tricky to solve, I am quite content with this puzzle.
Rules
Kurodoko rules: Shade some cells. No numbered cell may be shaded. A number indicates how many cells can be seen (including the cell itself) from that cell horizontally or vertically up to the edge of the grid or a shaded cell (whichever is reached first). No two shaded cells may share an edge. All the white cells must form a single orthogonally connected area. Japanese sums rules: Place the digits 1 to 7 (1 to 5 in the example) in some cells, so that no digit is repeated in any row or column. Numbers on the outside indicate the sums of consecutive digits in that row or column. The sums are given in the order they appear in the grid. Each sum is separated by at least one empty cell.
Additionally, empty cells of Japanese sums are shaded cells of the Kurodoko. Cells with circles may not be shaded and are valid Kurodoko clues once a digit has been entered.
Example
Puzzle
Japanese Sums (46 points)
This is probably my favorite puzzle of the set, at least from the classic puzzles. A downside is that it could be a frustrating puzzle if you don't spot the break-in, but I really like that piece of logic, and I don't remember seeing it in a Japanese Sums before (not claiming it has not been done before though). I was also very happy with the theming here, getting all question marks and all numbered clues on separate sides, with nice symmetry of clue layouts within each side, which took quite some tweaking to get it to work.
Rules
Place the digits 1 to 7 (1 to 5 in the example) in some cells, so that no digit is repeated in any row or column. Numbers on the outside indicate the sums of consecutive digits in that row or column. The sums are given in the order they appear in the grid. Each sum is separated by at least one empty cell.
Japanese Sums/Snake (24 points)
This feels like the most underrated (in point value) puzzle of the set to me. This was a fun combination to set, although it can be tricky to get the last few areas unique without giving away too much of the early logic. Luckily Japanese Sums lends itself towards question mark clues that can solve this issue. I also would have preferred to achieve symmetry with clues on the top, but due to the nature of this combination, it would also make the puzzle even more symmetric to solve. And sometimes good enough is just good enough...
Rules
Japanese Sums rules: Place the digits 1 to 7 (1 to 5 in the example) in some cells, so that no digit is repeated in any row or column. Numbers on the outside indicate the sums of consecutive digits in that row or column. The sums are given in the order they appear in the grid. Each sum is separated by at least one empty cell.
Additionally, the empty cells form a snake (i.e. a non-intersecting path that does not touch itself, even diagonally). The outside clues are all Japanese Sums clues and do not say anything about the snake itself!
Example
Puzzle
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