Comment by psoots

Honestly, there's nothing better than the Cracking the Cryptic app for sudoku, called "Sven's Sudoku Pad." People who love sudoku have congregated around that channel. It's updated regularly and there are a lot of puzzles that can be imported into it. It gives you very helpful pencil mark controls including colors and differently placed marks. There really just hasn't been another app that compares to the level of production for this Sven's.