If Sudoku puzzles are new to you, then this release will be particularly helpful.
Whether you loaded a puzzle from a library, keyed in a puzzle from a newspaper, created a random puzzle, or imported a puzzle copied from a variety of formats, a text log of how to solve the puzzle is produced by the Grader.
A look at the first few topics in the Fundamentals, plus following this log while you are solving a puzzle, teaches you how to solve them very quickly
The Fundamentals consist of a logical description of how solution strategies follow from the basic rules. This is considered important - hence the name of this App.
This logical description often results in grouping several strategies together because of their similar logical basis. Look at a topic title in the Fundamentals, and then see the several strategy names that many of them have in the subtitle.
The visual aid for chains introduced in Version 3 is a good example. All the commonly used chains are solved in the same way, based on a common attribute they all have that logically follows from the basic rules.
The 4 screenshots here from the Fundamentals show a user choosing one of the next links available to an XYchain.
The gold-colored hits are due to the hit seeing the circled ends of a subchain. These chain ends are strongly-linked;
one or the other must be a solution.
You can find puzzles like this as 1-star puzzles in the Extreme library. Dont be put off by the word "Extreme" - they are there because of the chain-related buttons provided only at that library level. Load and advance to that level to solve them.
Other features that you dont normally see in Sudoku apps include the ability to lift a pattern from a puzzle that you import, and then create a puzzle with clues restricted to that pattern.
Also Grader statistics for each level showing the strategies used to solve the puzzle at that level.
And text copied from the Grader Log that can be used to display solutions on your iPad graphically.