Reversi Bot is middle level AI, which can teach newcomers and fight with skilled. No any outgoing connections to servers, no VPN needed.
Like chess, crosswords, puzzles - reversi game is a good gymnastics for the brain. But for those who just press the keys, it will also work. It won't make a champion out of you, but at least it will amuse you.
This game will help you maintain mental clarity. It prolongs the activity of elderly people. Games of this kind are recommended by doctors as a prevention of Alzheimer's.