Today's genre is a lesser-known type from Eric Fox, a college student in the US who also invented Aqre, Voxas, and Disorderly Loop.
Rules: Shade some tetrominoes of cells so that no two tetrominoes touch each other orthogonally. Clued cells cannot be shaded, and a clue means that the first tetromino seen in a straight line in the indicated direction is of the shape associated with that letter.
In the first post introducing the Genre Spotlight, I included this phrase:
"There may also be types that were common ten or twenty years ago but may not be so popular nowadays! (Remember, I'm a pandemic-era puzzler!)"
Three months in, there haven't really been any genres that would fall in this category. Coral is probably the first. It's been a staple of WPC rounds since 2001, yet doesn't seem to be quite as popular at the moment. (Perhaps it has been supplanted by Cross the Streams.) Genres with only outside clues are not my favorite, but the extra structure provided by the coral creates some interesting dynamics.
Rules: Shade some cells so that all shaded cells form one orthogonally connected area and the unshaded cells are all connected orthogonally by other unshaded cells to the edge of the grid. No 2x2 region may be entirely shaded. Clues outside the grid represent the lengths of each of the blocks of consecutive shaded cells in the corresponding row or column, not necessarily in order.
Quick post today. As of writing this, my PhD defense is two (2) days away. By the time this post is live, I'll most likely be a doctor! Or something. (Edit: whoops, I forgot to schedule this post for Thursday! So, uh, you're getting these puzzles slightly in advance. Tomorrow's post has been moved back as a result.)
On an unrelated note, most of my puzzle energy has been spent preparing for this year's Logic Puzzle Open. If you're in the United States and would like to meet with other puzzle peeps at MIT in a month, feel free to swing on by! Several of us have been hard at work preparing for the event, and while we may be slightly tight on time, we'll guarantee a good time or your money back. (Spoilers: the event is free.)
With that said, on to our regularly scheduled Content. Today's genre is "Diagonal Chains", a type originating in the Innovatives round at WPC 2019.
Rules: Shade some cells to create diagonal chains. Shaded cells cannot be orthogonally adjacent, and no shaded cell can touch more than two other shaded cells diagonally. Furthermore, there can be no 'loops' of shaded cells – in other words, each group of diagonally connected cells must have at least one shaded cell with less than two diagonally touching shaded neighbors.
Cells with numbers cannot be shaded. The numbers indicate the sum of the lengths of all such chains where at least one shaded cell is horizontally, vertically or diagonally neighboring to the numbered cell.
This will be the last Inaba genre for now. I've found several hidden gems within the collection (including one that I'm saving for something more official!), but in general, his more obscure genres are difficult to construct puzzles for. Today's style was no different -- individual clues often aren't powerful by themselves, but every clue taken together creates a powerful effect, so you really need to carefully choose the numbers to make the solve work. That said, today's puzzle might actually be my favorite of all the Inaba types so far. Each clue can only see a limited distance away, but the interactions are more subtle than you might think.
This genre is sometimes called "Sandwich" by English speaking sources, bu that name is a bit silly, so I've chosen to go with its Japanese name "Santoitchi" instead. Apparently, "san to ichi" translates to "three and one" in Japanese, which fits the rules better. I don't know where the extra t came from, but oh well. Blame Google Translate.
Rules: Shade some cells so that no two shaded cells are orthogonally adjacent and divide the remaining unshaded cells into three-cell regions. Each region must contain exactly one numbered cell, which indicates how many shaded cells the region is orthogonally adjacent to.
I've noticed that all three Inaba genres so far have been loop/path puzzles. Naturally, some people might want some variety. Here's your variety: have a maze genre instead. Totally different, I swear.
Rules: Draw some borders to form a maze. The maze has two exits as indicated. The maze cannot contain any cycles, and all cells should be reachable. The maze doesn't have any 4-way intersection.
Each O indicates a 3-way intersection, and all intersections are marked. Each X indicates a dead end, and all dead ends are marked. The unique path through the maze passes through all intersections.
