(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 | |
|---|---|---|---|
 | Shikasudoku 2 by Qodec (on 12. February 2022, 12:09) | 59 |  95 % |
| Firework for Entropy No. 50 by Mad-Tyas (on 19. December 2023, 18:19) | 49 | 95 % |
| Doppler Effect (Roller Coaster) by Agent (on 3. January 2024, 09:00) | 51 | 99 % |
| Covert Confinement by SSG (on 21. January 2022, 07:01) | 43 | 98 % |
| It's all about sharing by Emphyrio (on 3. February 2023, 17:50) | 39 | 97 % |
| Schrödinger 201: Reversing Time's Arrow by ViKingPrime (on 20. September 2023, 01:00) | 39 | 94 % |
| X-sum, but in Chaos by SparkNights (on 21. September 2023, 06:00) | 41 | 96 % |
| A Ranked Phenomenon by Las4one (on 25. December 2025, 05:00) | 43 | 96 % |
| Lügner Rundwege - Liar Loops by Calavera (on 17. November 2009, 19:32) | 63 | 97 % |
| Primesweeper Sudoku by SenatorGronk (on 23. June 2020, 01:30) | 36 | 93 % |
| Little Miracle by Prof.Dori (on 13. May 2024, 18:26) | 98 | 97 % |
| Yin-Yang Killer by SirMoose (on 18. May 2024, 20:20) | 36 | 90 % |
| Stostone Cold (Chaos Construction) by Phistomefel (on 10. April 2024, 20:09) | 105 | 98 % |
| Roller Coaster mit Extras 8 by Uhu (on 19. August 2018, 10:12) | 57 | 98 % |
| Castle Wall / Yin-Yang #2 (13X13) by MagnusJosefsson (on 27. December 2022, 13:28) | 56 | 96 % |
| The Amazing World of Grkles by Playmaker6174 (on 31. October 2022, 03:10) | 33 | 96 % |
| Assassins by The Book Wyrm (on 8. November 2023, 00:14) | 27 | 93 % |
| Pinch Hitter by ViKingPrime (on 14. May 2024, 03:00) | 30 | 91 % |
| Olympic Rings by Jobo (on 5. August 2024, 01:14) | 99 | 96 % |
| Die Kryptos - S02E06: Summenbild Rundweg / Sudoku by tuace (on 16. March 2018, 15:10) | 41 | 100 % |
