(Very) Hard AND nice puzzles
The following list contains portal puzzles that have been rated as nice or very nice and that are difficult. These puzzles are recommended for experts - and allow some time to solve.
| Description | solved | Rating | |
|---|---|---|---|
 | Productivity Killer (BYOK+) by SeveNateNine (on 18. October 2023, 02:45) | 14 |  100 % |
| Double or Nothing Roller Coaster by KNT (on 16. July 2024, 16:31) | 15 | 96 % |
| Keep Talking [And No One Explodes] by zetamath (on 27. December 2021, 20:54) | 84 | 99 % |
| Hendiadyoin Sudoku by ICHTUES (on 17. October 2021, 06:00) | 21 | 94 % |
| Kodama by zetamath (on 20. January 2022, 04:32) | 41 | 98 % |
| Geometry Experiment 2 by Jeet Sampat (on 5. March 2023, 14:25) | 21 | 90 % |
| Red Bubbles by antiknight (on 12. April 2023, 22:35) | 21 | 91 % |
| Colossal Masyu Masyu-Sudoku by Christounet (on 8. October 2023, 21:52) | 37 | 99 % |
| Origin (Coordinate arrows/Negators) by dumediat (on 21. October 2023, 16:10) | 18 | 100 % |
| Remote Chaos by XeonRisq (on 4. January 2024, 19:00) | 18 | 95 % |
| Shadow (Cave Skyscraper Hybrid) by tallcat (on 20. November 2022, 09:00) | 53 | 97 % |
| The Unlikely Duos - A 6-pack Linked Sudokus Puzzle by Playmaker6174 (on 8. June 2022, 01:50) | 23 | 99 % |
| Arrow Laboratory by PotatoHead21 (on 20. January 2023, 15:12) | 25 | 96 % |
| ✚ Whisper-me-Sum-thing Loop ✚ by ElChiglia (on 9. December 2023, 07:15) | 26 | 93 % |
| Matroschka, grosse Version by pirx (on 5. February 2016, 18:00) | 43 | 97 % |
| Chaos II: The Two Killers by lerroyy (on 18. April 2022, 22:25) | 48 | 98 % |
| Deconstruction: Region Sums by Jay Dyer (on 24. April 2022, 22:14) | 45 | 99 % |
| Vault Construction by the_cogito (on 12. July 2022, 16:43) | 54 | 98 % |
| Equilibrium 2: The Rune by Mad-Tyas (on 13. December 2022, 09:42) | 28 | 93 % |
| Checkered Slitherlink by KNT (on 18. June 2024, 03:12) | 25 | 100 % |
