Brain Games - Boost memory power with free brain games
Kano - The educational computer and coding kit for all ages
Dualnback.works - Dual N-back is a specific brain training exercise, that's been shown by research - it might improve fluid intelligence.
Harry Potter Kano Coding Kit - Build a wand. Learn to code. Make magic.
Pixelogic - Daily Picross - Nonogram logic game with 5000+ puzzles and a daily puzzle
Lego Boost - Build + Code + Play