(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 | |
|---|---|---|---|
 | The Postman Problem by ThePedallingPianist (on 6. July 2023, 13:16) | 21 |  100 % |
| Schrödinger's Triplers by Oddlyeven (on 22. July 2023, 17:44) | 42 | 99 % |
| Typhon by Kafkapharnaum (on 24. August 2024, 19:41) | 20 | 100 % |
| Where are the cage totals? - Odd/Even killer sudoku (#5) by Mr.Menace (on 2. February 2021, 10:12) | 31 | 95 % |
| The Corners are Even Double - Double Arrow Even/Odd Sudoku by Mr.Menace (on 29. August 2022, 20:08) | 28 | 92 % |
| Chaos Construction: Arachne by tesseralis (on 24. September 2022, 08:20) | 28 | 98 % |
| Birefringence by Jay Dyer (on 25. August 2023, 20:46) | 59 | 95 % |
| Suguru Chaos Deconstruction #3: Whispering Palindromes by mathpesto (on 20. February 2022, 16:27) | 100 | 97 % |
| Aqres of Shikaku Country (9x9) by mathpesto (on 29. October 2022, 22:57) | 33 | 98 % |
| Induction (Nonconsecutive German Whispers Sudoku) by Phistomefel (on 14. June 2022, 09:05) | 123 | 96 % |
| Killer Quads by RockyRoer (on 19. September 2022, 03:14) | 44 | 100 % |
| The Lonely White Dot by XeonRisq (on 14. December 2022, 21:00) | 51 | 96 % |
| Summation U-Bahn by Agent (on 19. September 2023, 09:00) | 48 | 99 % |
| Quem Dixere Chaos by mathpesto (on 9. February 2022, 05:06) | 54 | 96 % |
| Tír na nÓg by Qodec (on 17. July 2022, 10:20) | 58 | 97 % |
| Japanese Nurikabe (1) by KNT (on 4. September 2022, 05:44) | 58 | 99 % |
| Even Lighting by Jay Dyer (on 15. February 2023, 23:02) | 63 | 97 % |
| Two Truths and a Lie by zetamath (on 20. September 2021, 14:48) | 147 | 98 % |
| Thermal Equilibrium (Chaos Construction) by Agent (on 19. July 2022, 09:00) | 93 | 100 % |
| Wichtelkalender 2013 - Oktober by pin7guin (on 1. October 2013, 00:00) | 26 | 92 % |
