Game Clock - Time Controls

There are five main types of Time Controls: (1) Fischer (invented by Bobby Fischer), (2) Bronstein (invented by David Bronstein), (3) Simple Delay, (4) Game Word and (5) Hour Glass. The first three time controls implement some sort of delay clock, a small amount of time that is added for each move. The reason is that with a sudden-death time limit, all moves must be completed in the specified time, or the player loses. With a small delay added at each move, the player always has at least that much time to make a move. The two types of delay clocks differ in how the delay is implemented. The last two time controls are somewhat different, as they do not rely on time delay, as explained below.

• Fischer—before a player has made his move, a specified time increment is added to his clock. Time can be accumulated, so if the player moves within the delay period, his remaining time actually increases. For example, if the delay time is five seconds, and a player has four seconds left on his clock, as soon as his opponent moves, he receives the increment and has nine seconds to make a move. If he takes two seconds to move, on the start of his next move he has twelve seconds. There is also a variant of this time control that adds the delay after a player makes his move (Fischer after), so the delay is added to the player's remaining time and is available for his next move. If however time runs out during his move, the game ends without the delay time being added. This variant prevents the player who is in time-trouble to take advantage of the extra-time.

• Bronstein delay—with the Bronstein timing method, the increment is always added after the move. But unlike Fischer, not always the maximum increment is added. If a player expends more than the specified increment, then the entire increment is added to the player's clock. But if a player has moved faster than the time increment, only the exact amount of time expended by the player is added. For example, if the delay is five seconds, the player has ten seconds left in his clock before his turn and during his turn he spends three seconds, after he presses the clock button to indicate the end of his turn, his clock increases by only three seconds (not five).

• Simple delay—when it becomes a player's turn to move, the clock waits for the delay period before starting to subtract from the player's remaining time. For example, if the delay is five seconds, the clock waits for five seconds before counting down. The time is not accumulated. If the player moves within the delay period, no time is subtracted from his remaining time. This time control is similar to a Bronstein with time added before the move.

• Word—it is a sudden death time control, without any increment nor delay. The difference here is that when the time expires by dropping to zero, a flag is set, and the clock immediately starts counting up without limit. This time control applies to games where the amount of time used after the allowed time can be subtracted from the player's score as a penalty, such as Tournament or Club Scrabble.

• Hour Glass—a player loses in this time control when he allows the difference between both clocks to reach the specified total amount. For example, if the total is defined as one minute, both players start their clocks at thirty seconds. Every second the first player uses to think in his moves is subtracted from his clock and added to his opponent's clock. If he uses thirty seconds to move, the difference between the clocks reaches one minute, and the time flag falls to indicate that he loses by time. If he has used twenty nine seconds and then pushes the clock's button, he has one second left on his clock and his opponent has fifty-nine seconds.