What's wrong with most Sudoku games on the Internet (and even in newspapers)?

What's wrong with most Sudoku games on the Internet (and even in newspapers)?

There are many Sudoku games available on the Internet. Unfortunately, just a few of them are good enough for meaningful playing. As there are no official standards for making quality Sudoku, there are many Sudoku games without any quality check. To design a good Sudoku puzzle is quite a hard task as there are too many (not so obvious) factors to consider. Most developers overlook them and the reason may be in Sudoku's visual simplicity - which deceptively suggests a simplicity at its core.

So, why computer Sudoku game is so hard to design?

Because three major and unrelated components need to be developed very precisely: Algorithm, Design and User Interface and Fun/Challenge component.

Let's have a look at all three problems which most Sudokus are doing wrong:

Problem #1 - Bad algorithm (no unique puzzles and wrongly assigned level of difficulty)

Bad puzzles don't have a unique solution or they have miscalculated level of difficulty. True Sudoku puzzle has only one (unique) solution which a player can reach using a logic alone. If a puzzle doesn't have a unique solution players are leaved to guess, which is boring and the Sudoku suddenly becomes a game of luck which it isn't by its definition.

Secondly, puzzles often have wrongly assigned level of difficulty (usually called easy, medium, hard, etc.) as algorithm miscalculates it - which confuses players which may find that solving a puzzle declared as "easy" may be a hard task and vice versa.

Why this happens? Most incorrect (poor) algorithms determine their levels of difficulty based on a computer logic, not human logic. These algorithms depend on one or two parameters which are enough for a computer program solver.

Correct algorithm (a solver made for humans) needs at least 5 parameters and many iterations to make a precise enough levels of difficulty. That process of calculating correct Sudoku puzzle can be very slow as it makes heavy load on the computer processor (CPU). Probably, this is one of the reasons why 5 parameters (and many iterations) are rarely included in the algorithm. Finally, it's important that human programmer fine tunes levels of difficulty manually, which also never happens.

Problem #2 - Bad design and user interface, missing multimedia elements

Sudoku games on the Internet have a bad design and user interface and are mostly unattractive. They have unintuitive game controls and unbalanced colors that break player focus and concentration which further slows him/her down in solving a puzzle.

Sudoku is known as visually simple game, but computers should enrich it with multimedia elements and pretty design.

Problem #3 - Lack of fun/challenge component (too heavy for beginners or too boring for advanced players)

In most Sudoku games on the Internet, fun/challenge elements don't go further than just changing levels of difficulty. But there must be more options, for any skill range.

For beginners it is good to have a smaller puzzle size from 4x4 to 7x7 and lot of helpful options for solving puzzles.

For advanced players more challenging and various options are needed, such as irregular regions (non-rectangular) inside puzzles, numbers being replaced with symbols or graphics, pattern shaped puzzles and so on.


Sudoku is still mega-popular puzzle game. But it needs quality basis to stand on. For now just a few Sudoku games can satisfy unwritten standards. Sudoku games that cannot guarantee a good playability simply need to be avoided.

Sudoku Arena solves all of the problems above and adds its own unique features not found anywhere else.

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