(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 | |
|---|---|---|---|
 | 8-Color Theorem by the_cogito (on 14. June 2022, 19:10) | 38 |  98 % |
| Extraterrestrial Tripleblock with X-Sums by KNT (on 27. May 2023, 16:45) | 36 | 100 % |
| Above Average On Average (Geometry Experiment 5) by Jeet Sampat (on 22. July 2023, 17:45) | 37 | 95 % |
| Matter by ThePedallingPianist (on 12. August 2023, 00:38) | 22 | 92 % |
| Build-Your-Own Kropki Sudoku by The Book Wyrm (on 15. January 2024, 20:58) | 52 | 95 % |
| Sorted Subway by KNT (on 22. July 2024, 07:21) | 40 | 96 % |
| Position Sums mit Average Arrows by glum_hippo (on 27. December 2024, 16:59) | 17 | 98 % |
| Tentrik Meditation (with mellowrobinson) by sujoyku (on 3. August 2025, 08:29) | 39 | 97 % |
| GW-Bahn (German Whisper U-Bahn) by cyddrdrd (on 27. September 2025, 00:00) | 19 | 100 % |
| Fillomino-ish Killer Sudoku by SirWoezel (on 25. November 2020, 16:21) | 55 | 99 % |
| Three of Diamonds by zetamath (on 20. February 2023, 16:07) | 55 | 93 % |
| Seesaw (Killer Only Sudoku) by Celery (on 10. December 2023, 22:34) | 55 | 98 % |
| Too Close For Comfort by Niverio (on 3. March 2024, 16:11) | 53 | 96 % |
| Japanische Summen-Koralle 2358 by Uhu (on 27. December 2016, 14:23) | 55 | 98 % |
| Schrödinger's Arrows by starwarigami (on 14. January 2022, 04:34) | 30 | 96 % |
| Kill Kill (Doubler Killer) by ICHTUES (on 28. August 2022, 06:00) | 61 | 98 % |
| 195? 519? 951? by twototenth (on 20. September 2022, 08:00) | 58 | 97 % |
| I'm going deeper underground... [Snake U-Bahn] by Christounet (on 1. December 2023, 14:13) | 30 | 98 % |
| Unique Value Deconstruction by sfushidahardy (on 27. June 2024, 18:13) | 32 | 96 % |
| Twin Killer Sudoku III by Richard (on 8. July 2009, 14:19) | 89 | 93 % |
