The "hot seat" concept was popular in multiplayer strategy computer games before the Internet boom. It means that the game is played in front of a single screen and keyboard and you should not see the movements of your opponent. When playing head-to-head, this usually means that your friend has to leave the room, or at least turn his back. If you stay near the computer and just turn your back, audio clues may give you certain tip-offs. Novadays most multiplayer games have an Internet gaming option so the hot seat method is not used that much anymore. While Internet makes it simpler to play these games, I think it somewhat flattens the gaming experience because the atmosphere of fiery competition is not the same when you are not head-to-head with your opponent.