Apple has lots of games, some demos, some shareware, some freeware. 

Arcade Town has games you can download or play online  

Childtopia has tons of games. You can select the category: memory, music, numbers, language, creativity, observation and more. All are online, and most have several levels. Very little reading required. You can also switch the language to Spanish or French.

Number Games

UniSodoku 1.7

Play the popular game of Sudoku on your Mac with UniSudoku. Enjoy the best aspects of the pencil and paper puzzle with all the advantages of playing on your computer.

• Unlimited puzzle generation
• No messy handwriting!
• Full Undo/Redo support, no more erasing!
• Requires Mac OS X 10.3.9 or later

 Letter Games

Pat Sajak has some fun games-something similar to Wheel of Fortune

Word Games

Owl and Mouse Early reading software—phonics software, alphabet games, and Dolch sight words in a fairy tale story.  All of it FREE!  Free online USA maps, world maps, map of Europe, map puzzles of the US, Europe, Africa, Asia, and many more.  You can build your own castle and coat of arms—free downloads.