two free Sudoku games for Java Mobile phones
Some days ago, my wife and I traveled by train. There were a lot of passengers who were writing on papers. Some were playing crossword puzzle, others were playing Sudoku (I learned this term later). There were dozens of free papers left on the train and my wife picked up one to try the Sudoku game on it. After a while, she found it a little bit difficult then asked me to solve it with her. It was really challenging…
I searched on Google and found more information about the Sudoku game:
“The term ‘Sudoku’ comes from Japanese, it was invented by Switzerland mathematician Euler. It was developed in US and Japan later. Since 2005, Sudoku becomes popular in European countries: thousand of papers provide Sudoku games, there are TV shows about Sudoku and Sudoku online…
The rule of Sudoku is quite simple, there are already some digits on a 9X9 matrix, the player needs to fill digits from 1 to 9 into rest grids, each digit can only appear in each line, column and 3X3 sub matrix once.”
There are systematic solutions can be found on the internet.
I found two good free Sudoku software for Java-enabled mobile phones from Getjar: 5ud0ku and SudokuSpot。Among numerous Java Sudodu games, advantages of these two are low resource usage (they can run on low-end mobile phones), while their GUIs are still quite pretty and support keyboard and touchscreen at the same time. I don’t need to worry that there is no enough room for inter medium steps anymore 
The introduction of 5udoku on Getjar is as below:
5ud0ku is Sudoku Game Midlet.
It generates and solves puzzles for the popular Su Doku game. You can also input and store your own puzzles.
There are some hint-features within the game, as well as options to adjust colors and behaviour. On devices equipped with a pointer, an alternative input method is offered.
It`s Freeware and licensed under LGPL.
You will need MIDP1.0/CLDC1.0 with 128×128 pixels at least to run the midlet. Midlet may run slow on `older` phones.
It features:
- Sudoku game for 9×9 grids
- game creator (three difficulty levels)
- game editor and game solver
- colored digits and colored pencilmarks
- supports pointer-devices (Smartphones/PDA)
- four different display sizes (auto adjusting)
- autosave/load, load and save of games
- undo/redo mode
- game generation can be customized
- some colors and layout can be customized
- solving time status display (*-key)
- helper: check puzzle (highlights correct/wrong cells)
- helper: beginner mode (automatic pencilmarks)
- helper: calculate pencilmarks
- helper: show specific digit
- helper: signal (obvious) conflicts
- helper: display solution
- helper: show possible digits in sidebar (depends on display size)
- helper: show remaining digits in sidebar (depends on display size)
- languages: english, german (extended version also hungarian, polish, slovak)
Download links of them are
5ud0ku：JAD file (5ud0ku.jad)，JAR file (5ud0ku.jar)
SudokuSpot：JAD file (SudokuSpot.jad)，JAR file (SudokuSpot.jar)
I enjoyed reading what you wrote, you should give http://www.sudokulive.net a look for Sudoku puzzles.