Brain games are fun indoor activities. I teach my grandchildren brain teasers and puzzles. My 8 year old grandson loves Sudoku while his 11 year old brother prefers crossword puzzles. He has printed them online for free at freedailycrosswords.com. He compiles it all and he's really good at it. Sometimes he also makes his own crossword puzzles and share them to his classmates. I'm so proud of him.