### Puzzle #24

This is The Terrifying Torus, an original mashup puzzle. Rules are given below the image.

Difficulty: hard

Theme: Secret Santa Gift for TheGreatEscaper

PDF

Swaroop Penpa (To have the answer checker confirm your solution, all lines, and only those lines, that lie in the centre 16x16 grid must be drawn.)

Rules: The puzzle is the centre 16x16 grid. It is divided into four 8x8 quadrants, and is toroidal, so the left and right sides connect to one another, as do the top and bottom sides. Faint copies of the adjacent grids are added for convenience.
Draw a single loop, whose vertices are grid vertices, that doesn't branch, and whose segments may travel in any direction, not just compass directions. Each visit of the loop to a region must contain a turn. Additionally, if any segment lies in a quadrant, then it must obey the rules of that quadrant:
• The top left quadrant is Kouchoku: Every loop vertex in this quadrant must be at a clue. Every visit to this quadrant must begin and end on a dot. All copies of the same letter must be connected by a path passing through no other dots or letters, and different letters may not be connected. All dots and letters must be used by the loop. A 180° angle at a vertex is allowed in this quadrant. The loop may intersect itself in this quadrant, but ONLY at right angles. (Colouring is for cosmetic purposes only.)
• The top right quadrant is Keima Loop: Every loop vertex in this quadrant must be at a star. Pass through all stars, using only edges that are knight moves. A 180° angle at a vertex is allowed in this quadrant, but the loop may not intersect itself in this quadrant. Note that any loop segment going into or out of this region must be a knight move as well.
• Bottom left quadrant is Total Omnidirectional Midloop: Pass through all dots, such that each dot is the midpoint of an edge. All dots are given. The loop is not allowed to have a 180° angle in this quadrant, nor may it intersect itself in this quadrant. (Note that any loop segment going into or out of this region must be clued with a dot.)
• Bottom right quadrant is Angle Loop: Every loop vertex in this quadrant must be at a clue and vice versa. A triangle indicates that the angle at that vertex is acute; a square, right; a pentagon, obtuse. The loop is not allowed to have a 180° angle in this quadrant, nor may it intersect itself in this quadrant.

Another Secret Solver puzzle from Puzzlers Club; this time for 2020 and TheGreatEscaper. No solution or example is provided this time, because frankly I can't be bothered.

As with the previous one, I'm giving this a "hard" simply because two of these genres are novel, and non-orthogonal loops are generally not a thing people are fine with dealing with.

Special thanks to SoftFro for typesetting this in Tikz, and to montelucci, rand_yosh314, jkittykitkat, Jamie Hargrove, boboquack, Deusovi, and SoftFro once again for testing this.

### Puzzle #23

This is a Kurodoko puzzle.

Difficulty: hard

Theme: logical

Found this one deduction in a different puzzle, made a puzzle to properly exploit it. If you know what you're looking for, though, this is a breeze.

### Puzzle #22

This is a Masyu puzzle.

Difficulty: extreme

Theme: None

This was originally made to showcase one particular deduction, but I accidentally made it too hard and bashy while trying to remove cooks. Oops. Well, hopefully it's still not too bad...

### Puzzle #21

This is a Yajilin puzzle.

Difficulty: medium

Theme: No Blacks?

Inspired by two Yajilin puzzles on a similar theme by Twitter user @agnomy. There are two main ways people have found to get to the solution, and neither are that easy.

### Puzzle #20

This is an Numbered Arrows Mashup Loop puzzle, an original mashup genre. Rules are given below the image.

Difficulty: hard

Theme: Secret Santa Gift for IHNN

PDF

Puzz.link (Note that the answer checking and clue colouring are nonexistent here, since this merely uses the Yajilin interface.)

Rules: Draw a loop through non-clue cells and shade the unused cells. Shaded cells may not be orthogonally adjacent (as in Yajilin). Each arrowed clue has a “line of sight” in the given direction, up until the edge of the grid. In addition, each quadrant's clues behave differently:
• Clues in the top-left quadrant are Yajilin clues; they indicate the number of shaded cells in the clue's line of sight.
• Clues in the top-right are Castle Wall clues; they indicate the total length of the loop segments along that clue's line of sight.
• Clues in the bottom-left quadrant are Slalom Count clues; they indicate the number of times the loop passes straight across the line of sight of the clue without turning. (Note that this type of clue does NOT count occurrences of the loop passing through the line of sight when turning, and that the loop is allowed to behave in this way regardless.)
• Clues in the bottom-right quadrant are First Seen Geradeweg clues; they indicate the length of the first-seen loop segment; if the first-seen cell used by the loop is a corner, both segments incident to that corner must be of that length.
(The small images around the puzzle are to remind you what each clue does.)

Below is an example and its solution:

I actually constructed this one for Puzzlers Club's annual Secret Solver event last year and only just got around to posting it now. Secret Solver is our version of Secret Santa, wherein everyone participating writes a puzzle for someone else. In this case, I had to write a puzzle for IHNN.

A full walkthrough and writeup can be seen here (but please don't read it until you've at least had a good crack at the puzzle). Many thanks to SoftFro for creating the images and PDF.

Even though, having constructed it, I think it's a medium, I'm rating it as "hard" just in case, and in part due to the fact that two of these genres are novel.

Anyway, I should probably get around to porting most of my puzzles to this blog (except maybe the ones I'm submitting elsewhere?). I've been constructing puzzles occasionally for the last 6 or so years, so I *should* have a pretty reasonable backlog. (Then again, a ton of them are "easy" by my standards and I don't necessarily want to flood the blog with them...)

### Puzzle #19

This is a Look-Air puzzle.

Difficulty: easy

Theme: Algorithmically Generated

Puzzlers Club has recently been experimenting with generating puzzles via the simple algorithm of "place a clue in the first spot where it can go, then repeat". Here's a Look-Air generated by placing a "2" in the first cell in reading order that could contain one legally (and which would give information).

### Puzzle #18

This is a Heyawake puzzle.

Difficulty: extreme

Theme: Filled Empty Space

Recently learned about an advanced Heyawake deduction. Here's my take on it. In addition, this puzzle requires bashing (or some deduction I haven't figured out yet). That's why this puzzle merits an "extreme" rating and not merely a "hard" rating. You have been warned.

Many thanks to rob and Freddie Hand for proving this unique.

### Puzzle #17

This is a Castle Wall puzzle.

Difficulty: medium

Theme: Logical

Just a puzzle I decided to make, using a Castle Wall deduction I don't seem to see too often. In general, I find that most Castle Walls available tend to use only deductions I consider "easy", so hopefully this will introduce you to a deduction you might not have known. Then again, given who likely reads this blog, I'm guessing that most of you already do know this deduction...

Rules link is to MellowMelon's blog; he created this puzzle genre. I'm sure there's MUCH more potential in this genre than the deductions I already know of and have seen elsewhere, though.

### Puzzle #16

This is a Cipher Hashiwokakero puzzle, a variant of Hashiwokakero. In addition to the rules of Hashiwokakero, each number has been replaced by a letter. Different letters refer to different numbers, and the same letters refer to the same number.

Difficulty: medium (not actually an Evil Zinger)

Theme: Bridge X-tension

Puzz.link link. (Note: Because Puz-PRE does not use letters in Hashiwokakero, all Xs in the puzzle have been replaced by blank islands in the link. Puz-PRE does not have the "same letters refer to the same clues" constraint programmed in, so the solver may mark incorrect answers as correct.)

Puzz.link does not support letters in Hashiwokakero, I had to manually add all the Xs in Paint.NET.

So yeah, this puzzle isn't quite as EZ as a normal Evil Zinger as I would have liked. Shame.

### Puzzle #15

This is a Masyu puzzle.

Difficulty: medium

Theme: Logical

Have a Masyu puzzle I constructed on request from an acquaintance. No clue how often I'll keep updating this blog, but I think I have something for here that I should probably post at some point.