GCompris is an educational software suite with numerous activities for children aged 2 to 10. Some of the activities are game-orientated, but nonetheless still educational. These include computer discovery (keyboard, mouse, different mouse gestures), algebra (table memory, enumeration, double entry table, mirror image), science (the canal lock, the water cycle, the submarine, electric simulation), geography (place the country on the map), games (chess, memory, connect 4, oware, sudoku), reading practice, and others (learn to tell time, puzzles of famous paintings, vector drawing, cartoon making, etc.). It currently offers in excess of 100 activities, and more are being developed.
Sudoku Sensei is not a Sudoku solver, but an "explainer". It can list the logical steps taken. It can generate new Sudokus and rank their difficulty. It supports not only 9x9 grids, but MxN, samurai, or any layout you can describe with the board editor. It has a GUI, manual, tutorial, and examples.
TuxWordSmith is similar to the classic word game "Scrabble", but with Unicode support for multiple languages and character sets. The game is currently distributed with 42 dictionary resources for playing Language[i]-Language[j] "Scrabble". For example, if configured to use the French-German dictionary, then the distribution of available tiles will be computed based on frequency of occurrence of each character of Language[i] (French), and, for each submission, the corresponding definition will be given in Language[j] (German).