Diabolical only — extreme excluded
Generates candidate puzzles and solves each one with the same logical solver as before, but this version applies a stricter filter: any puzzle that needs an AIC, a Forcing Net, a Finned Swordfish, a Grouped X-Cycle, an ALS-XZ, or any other Extreme-tier technique is discarded immediately. What's left is then required to actually need a genuine Diabolical-tier technique (Jellyfish, 3D Medusa, BUG Type 1, or XY-Chain) AND to have needed at least 6 total higher-level solves (anything above basic singles/pairs/pointing) — so what makes it through isn't just a puzzle that happens to touch Diabolical once, but one with real sustained depth.
Difficulty is graded by the hardest technique actually needed to solve the puzzle — see the tier table at the bottom of this page. These puzzles are genuinely rare under this filter (roughly 1 in 100 random attempts), so finding 5 can take a minute or two. Progress updates live below; use Stop to keep whatever's been found so far.
Puzzle readout