(This post is part of: “A Story of Self-setting Sudoku”.)
Here is another challenge that was hidden within our Sudoku puzzlehunt. We’re setting up a live endgame stream later this year with the winning team of the puzzlehunt, and wanted to share more of the special puzzles they solved in advance.

After solvers discovered and interacted with a Google Doc here, they got a set of apparent Cave puzzles. Note: this puzzle resolves to a 9-letter string but not an English word/phrase so without playing in the puzzlehunt this won’t have meaning to you.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Rules: In these caves, horizontal portals lead to horizontal portals, and vertical portals lead to vertical portals, with orange going to blue and vice versa. No portals in midair; always have them attached to a wall of the cave.

Note: Comments on the blog are great! For a more interactive discussion, please also consider using our Twelve Months of Sudoku? post on the GMPuzzles Discord. Not a member of the Discord? Click this link for basic access.