(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 | |
|---|---|---|---|
 | Colossal Cave U-Bahn by Agent (on 29. April 2025, 09:00) | 38 |  100 % |
| Crystalline Entity by IcyFruit (on 22. May 2025, 13:23) | 64 | 91 % |
| Chaos in the Knighttime by SenatorGronk (on 5. October 2022, 15:56) | 23 | 99 % |
| Parity Party XXV, "Gray's Anatomy" by glum_hippo (on 29. December 2022, 03:46) | 21 | 96 % |
| Berlin by zetamath (on 13. March 2023, 04:08) | 27 | 90 % |
| Times Square (CTC Secret Santa 2023) by alexc (on 11. March 2024, 01:34) | 11 | 95 % |
| Roller Coaster of Emotions by Agent (on 25. December 2024, 09:00) | 36 | 100 % |
| Sandwich Pseudoku by starwarigami (on 27. January 2025, 06:43) | 12 | 91 % |
| Constantinoqle (V-Bbhn witg Nestimg Ckues) by sfushidahardy (on 27. August 2025, 18:54) | 12 | 100 % |
| Chaos Construction: Miracle on 81 Cells by Playmaker6174 (on 17. September 2025, 07:00) | 38 | 98 % |
| Shambhala by IcyFruit (on 20. October 2025, 11:34) | 82 | 96 % |
| U-Bahn Aqre (ft. Christounet) by cyddrdrd (on 17. January 2026, 00:00) | 10 | 100 % |
| Chaos Construction: Aquarium (2) by KNT (on 23. June 2022, 01:08) | 66 | 98 % |
| Arrow/Group Sum Sudoku by ahaupt (on 10. July 2020, 21:53) | 67 | 99 % |
| Four Alien Theorem (Build Your Own Killer Sudoku) by Agent (on 7. April 2023, 09:00) | 56 | 99 % |
| Pentominous U-Bahn by KNT (on 17. November 2024, 02:15) | 47 | 95 % |
| Sudokuvania: Digits of Despair (v1.1.1) by SkepticalMario (on 4. April 2025, 02:27) | 303 | 100 % |
| Sandwich Sudoku by kolot (on 15. July 2021, 18:33) | 36 | 96 % |
| U-Bahn under Tripleblock for polar by KNT (on 1. January 2024, 08:23) | 31 | 97 % |
| Subway To Hell by Piatato (on 27. January 2024, 15:45) | 33 | 100 % |
