(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 | |
|---|---|---|---|
 | First Hidden Skyscraper Sudoku (Full Odd) by Feadoor (on 11. February 2020, 15:42) | 46 |  97 % |
| Serial BoX by twototenth (on 23. November 2021, 08:00) | 48 | 96 % |
| Internal X-Sums (Chaos construction) by Oripy (on 14. April 2025, 12:00) | 95 | 98 % |
| Shindig Redone (Anti-Knight, Renban) by juddimal (on 4. January 2025, 00:43) | 104 | 98 % |
| Framing In The Park by Niverio (on 14. April 2023, 19:33) | 43 | 96 % |
| Chaos Deconstruction: Japanese Sum Cross the Streams Cipher by abed hawila (on 30. March 2023, 17:02) | 49 | 97 % |
| Killer Pairs (White) by Yawnus (on 18. April 2026, 07:39) | 42 | 94 % |
| Reticulated Python by mathpesto (on 27. March 2022, 04:58) | 98 | 97 % |
| Is V Greater Than, Less Than, or Equal to 5? (Original) by HalfBakedLunatic (on 6. May 2024, 00:00) | 58 | 95 % |
| Friendly Borders by Prof.Dori (on 15. August 2024, 23:58) | 48 | 92 % |
| Hole Lotta Lots (Black Hole) by gdc (on 14. November 2025, 15:14) | 48 | 98 % |
| Circle of Stars (Renban Quadruples) by Tyrgannus (on 4. April 2023, 21:33) | 56 | 92 % |
| The Female of the Species... by Abdul the Killer (on 5. March 2024, 12:34) | 109 | 97 % |
| Killer Little Killer Sudoku by Willy Wonka (on 18. August 2020, 15:27) | 50 | 95 % |
| Denver by zetamath (on 7. April 2023, 16:37) | 105 | 98 % |
| Extemporaneous by NicoD (on 4. September 2025, 05:30) | 54 | 97 % |
| Coelacanth by Kafkapharnaum (on 1. April 2023, 20:20) | 67 | 98 % |
| Octagonal by 99%Sneaky (on 8. March 2026, 23:26) | 63 | 95 % |
| RAT RUN 29: Counterbalance by marty_sears (on 11. March 2026, 03:31) | 504 | 99 % |
| Japanisches Memory by ibag (on 26. September 2014, 20:37) | 48 | 99 % |
