(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 | |
|---|---|---|---|
 | Palindrome Killer Sudoku by udukos (on 8. August 2020, 23:02) | 41 |  94 % |
| Rigel (Arrow Sudoku) by emmettcito (on 27. April 2021, 17:01) | 42 | 98 % |
| Antiknight Between Lines by Gliperal (on 12. May 2021, 04:19) | 43 | 97 % |
| Witchcraft by PotatoHead21 (on 25. November 2021, 21:56) | 39 | 98 % |
| 8-Color Theorem by the_cogito (on 14. June 2022, 19:10) | 39 | 98 % |
| Above Average On Average (Geometry Experiment 5) by Jeet Sampat (on 22. July 2023, 17:45) | 37 | 95 % |
| Build-Your-Own Kropki Sudoku by The Book Wyrm (on 15. January 2024, 20:58) | 52 | 95 % |
| The Big One by IcyFruit (on 25. January 2024, 14:04) | 46 | 94 % |
| Tentrik Meditation (with mellowrobinson) by sujoyku (on 3. August 2025, 08:29) | 45 | 97 % |
| GW-Bahn (German Whisper U-Bahn) by cyddrdrd (on 27. September 2025, 00:00) | 21 | 100 % |
| Fillomino-ish Killer Sudoku by SirWoezel (on 25. November 2020, 16:21) | 55 | 99 % |
| Prime-Co Sweepers by XeonRisq (on 11. January 2023, 17:00) | 49 | 100 % |
| Seesaw (Killer Only Sudoku) by Celery (on 10. December 2023, 22:34) | 56 | 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 % |
| Wheel of Fortune by Qodec (on 4. September 2020, 13:34) | 35 | 96 % |
| 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) | 31 | 98 % |
| Asterias (Pentopia U-Bahn) by MaizeGator (on 22. July 2025, 05:19) | 31 | 96 % |
| Sirius by jovi_al (on 19. February 2022, 03:07) | 44 | 99 % |
