Rorschach's River

Rorschach’s River is a large line-drawing pen-and-paper puzzle involving 50 different sets of rules. The goal of the puzzle is to draw a single path that satisfies every consecutive ruleset, from the entrance of the grid at the very top to the exit at the bottom. Solving the full path is a memorable journey of challenging deductions and surprising ideas.

Each of the 50 sections that compose the puzzle follows a precise ruleset. Some of the rulesets are fairly straightforward and may be familiar to players experienced with path puzzles. For instance, the first section follows “Simple Path” rules: the path must visit every white cell in the section. Another section follows “Midpath” rules: the path must pass straight through every circle in the section, and each circle must mark the center of the straight line segment it lies on.

Other rulesets are more exotic, like “Area 51” (which involves cacti, aliens, and four other types of clues) or “Alternating Kouchoku” (which involves oblique angles between path segments and conditional intersections). Each section was designed by a different author, and some of the rulesets were specifically developed for the project. Despite the solution being highly twisty and irregular, there’s a consistent theme of clue locations obeying horizontal symmetry throughout the whole puzzle (as per its Rorschach namesake). All sections can be solved solely through logical deductions, and the final path is rigorously unique.

The puzzle’s novelty and complexity goes beyond the individual rulesets though. One of its main quirks comes from the absence of any blocking border between the sections, implying that even after the path exited a section through one column, it can still re-enter through another column, and exit again through a third one. Indeed, clearing a full section often requires to start solving the next section at some point, in order to pin down these returning strands.

Another defining characteristic of the puzzle is that the consecutive sections actually overlap by three rows every time. These rows can provide clues relevant to both sections, with both rulesets applying. This is a design fixture of mash-up puzzles, appearing for instance in Sudokuvania 2: Lineage of Logic and Super Sudokoid: Final Transmission. Since these hybrid sections are more constrained than the other areas, they lend themselves to singular deductions without being necessarily complex.

Rorschach’s River is available both as a printable document and as a browser game. The puzzle can be solved without prior knowledge of the various rulesets, though some familiarity with the line-drawing genre can be helpful. Whatever your situation, some sections are quite challenging, and you’ll have to explore and keep in mind the consequences of every rule. Advice and tricks about each ruleset are provided on the game’s website in the form of hints, and the full solution is also available as a very, very long file in case you need additional help.

This description was written by Oriane Tury.