These are the last and the hardest puzzles I have in my Vertigo backlog. I encourage you to try easier puzzles in earlier posts if haven't done them yet. Help yourself to spoilers in square brackets, [like this].
Rules
Draw a single loop travelling orthogonally through the centers of all empty cells. The loop may visit some cells twice, but must travel straight through such cells each time. The loop can not otherwise self-overlap or self-intersect.
While travelling along the loop, all 90 degree turns must have the same direction (all left or all right).
While travelling along the loop, all 90 degree turns must have the same direction (all left or all right).
Jet
- [Any region in the board must be entered an even number of times. This is commonly used on partially walled off areas, but occasionally can be helpful for small regions which already have almost all possible entrances determined.]
- [A deep lookahead is required to resolve the top right corner near the end.]
Cyclone
The second Vertigo I've made.
- [Entrance parity is stronger in Vertigo than most other loop genres. Naturally a 1-wide gap contributes one entrance, but also a 2-wide gap always contributes an even number of entrances (0 or 2) since the S-shape is forbidden.]
- [A 3-wide gap that must contribute an even number of entrances is very constrained. Start by looking if it can separated into smaller gaps.]
Speakeasy
- [In addition to the usual entrance parity, in Vertigo (and some other genres like Ring Ring) there's also directional parity: the number of lines turning clockwise and counter-clockwise among those that enter a region must be equal, as each visit to the region starts and ends with opposite directions. This is easiest to apply in the bottom left corner, but is helpful throughout the solve.]
Difficulty: [★★★⯪☆]
Featherweight Minstrel (extra)
Third Vertigo I've made. It has to be my favourite one simply because of how minimal and rich it is.
The "extra" part comes from the fact that my initial puzzle was less minimal and very slightly easier, but I also knew that the minimal version is unique. It took the help of CtC members to find a path with awesome new logic (thanks, Kays!)
- [The break-in is in the middle right. Regarding of how the central horizontal line turns, something at the right side is forced.]
- [For the bottom right (and this the Kays' contribution), apply entrance parity to 4-wide gaps that are crossed an odd number of times. There's still some elbow grease required to resolve everything, but this deduction simplifies it a great deal.]
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