The idea of the game, think of anything, and that literally means anything, from your next door neighbor to a tub of lard, then answer the questions the 25Q throws at you as honestly and accurately as you can. The twenty questions will be answerable with either "yes", "no", "sometimes" or "don't know".
The artificial intelligence behind the game is a neural-network, similar to a human brain. A brain, or neural-network, is built from neurons connected by synaptic connections. A human brain has about one hundred trillion (100,000,000,000,000) synaptic connections. The 25Q. net online version has about ten million (10,000,000), and the pocket version has about two hundred and fifty thousand (250,000). The game uses the neural-network to choose the next question as well as deciding what to guess.