(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 | |
|---|---|---|---|
 | Minister of Primes (featured on CtC) by Mountainfarmer (on 6. August 2022, 11:19) | 38 |  94 % |
| Double Decker Sandwiches by RockyRoer (on 19. November 2022, 12:58) | 39 | 94 % |
| Killer ratio by jcgodart (on 23. October 2024, 09:38) | 35 | 92 % |
| Latent Entanglement by 99%Sneaky (on 14. February 2025, 18:15) | 81 | 96 % |
| Toroidales Tapasyu 2 by usp (on 25. October 2014, 00:00) | 59 | 98 % |
| Shrug by zetamath (on 15. December 2022, 16:33) | 118 | 97 % |
| Woof! by zegres (on 1. August 2022, 07:13) | 79 | 97 % |
| PYRAMIDE - Buchstabenrätsel / Letter puzzle by DocLogic (on 3. February 2020, 18:21) | 37 | 95 % |
| Dense Populations by Mark Sweep (on 5. March 2021, 10:00) | 22 | 97 % |
| A + N ∞ (Palindrome + kropki sudoku) by Aspartagcus (on 16. July 2021, 00:02) | 21 | 97 % |
| 4'33" by ndsurgenor (on 28. September 2021, 15:35) | 36 | 97 % |
| Just Knights and Arrows by GBPack (on 18. November 2021, 21:53) | 23 | 90 % |
| Nonconsecutive Palindrome Sudoku #1 by GBPack (on 24. November 2021, 22:15) | 20 | 92 % |
| This is it. I've done it. by EricRathbun (on 23. April 2023, 00:19) | 59 | 97 % |
| Walkie Talkie (choco banana-ten lines sudoku) by Ambrose (on 26. January 2025, 00:00) | 16 | 94 % |
| GCF by RockyRoer (on 14. February 2025, 14:39) | 17 | 97 % |
| Petit Pois by ThePedallingPianist (on 7. May 2025, 10:55) | 68 | 94 % |
| Calembour by Jobo (on 28. May 2025, 09:01) | 38 | 94 % |
| 9-Region Thermometers: An Extreme Limitations Puzzle by Md88keys (on 12. July 2025, 21:48) | 113 | 95 % |
| Entropy miracle 3 by fractalminding (on 27. January 2026, 09:59) | 44 | 94 % |
