BrainTeaser is a British game show, first broadcast in 2002. As of 2006 it airs on five between 12:30 and 13:45 Mondays to Fridays and is presented by Alex Lovell and Jonathan Gould, who generally take turns week by week. Craig Stevens and Rachel Pierman also used to present the show regularly; in December 2005, Craig has returned to presenting it occasionally.

Unlike most game shows, BrainTeaser is live, with phone-in games being provided for the viewers throughout the show in addition to the studio game.

Format
Four contestants play in each show. The structure is that of a knockout tournament, with all four constestants playing the first three rounds, two at a time, and the winners going into the "semi-final".

Except for the pyramid game, all rounds are on the buzzers, with the opponent given a chance to answer if the player who first buzzed in answers incorrectly.


Rounds played by all contestants

Scramble
Words of eight or more letters are partitioned into four or five pieces, rearranged and presented to the contestants, who must unscramble them. Only five points per correct answer are scored in this round. In all other rounds, each correct answer scores ten points.


Crossfire
This is a general knowledge crossword game. The computer randomly selects the first clue to be presented to the contestants. The player who correctly answers each clue then chooses the next clue to be solved. If neither player can give a correct answer, the answer is revealed and the next clue is chosen randomly again.

Prior to 2005, this was not a quick-fire round. Instead, one player had control at a time, starting with the player who scored the most points in Scramble. The player who has control had the first attempt at answering each clue, and control passed only when a player failed to answer correctly. If neither player could give a correct answer, the control stayed with the second player to whom it was offered.


Trio
Three letters are given. Contestants must give a word that contains the three letters in the given order.

This is similar to the main game principle in Catchword and the In a Spin round of Masterteam. However, there are two differences:

The first given letter need not be at the beginning of the word. 
The second and third letters may not occur prematurely, even if they also occur in the correct sequence. For example, given the letters C L O, the word "colour" is not allowed, since an O occurs before the L. 
Trio was introduced in 2005 to replace a round known as Word Play, an anagram round in which the solution was revealed letter by letter until a contestant buzzes in.


Semi-final rounds
The two winners of the first three rounds play the semi-final. Despite the name, there is only one semi-final, which determines the winner of the show - the "final" is the solo pyramid game. Both contestants start the semi-final from a score of zero, regardless of the points they scored in the previous rounds.

Prior to 2005, Wordstorm was played before Clued Up.


Clued Up
This is a general knowledge round. Contestants must identify something (a famous person, TV show, film, place, etc.) from the clues. First the category appears, followed by four short clues revealed one by one. If a contestant buzzes in but fails to give the correct answer, all four clues are revealed to the other player.


Wordstorm
Contestants must find a word with the given number of letters and the given first and last letters.


Pyramid
The winner of the semi-final plays the solo pyramid game. The player must find words of increasing length, each of which adds a letter to the previous word. The initial three-letter word is given, and for each word the new letter is given in its correct place; the letters of the previous word are rearranged to arrive at the new word. Sometimes there may be more than one word that fits the letters, but only one word is the correct one.

The contestant has 45 seconds to complete the pyramid, and there is no limit on the number of words the contestant may try before arriving at the correct one. When each word is correctly identified, the clock stops and the player may choose to continue or to stop and take the winnings. If the player chooses to continue, then the new letter is revealed and the clock started again from where it left off. If the player then fails to get the word within the remaining time, he/she wins only £100. The prize money for a contestant who stops and takes the money (or who completes the pyramid by getting the eight-letter word) is as follows:

4-letter word: £200 
5-letter word: £500 
6-letter word: £750 
7-letter word: £1500 
8-letter word: £3000 
Before 2005, there was no prize money for a contestant who runs out of time while playing the pyramid.


Phone-in games
There are two kinds of phone-in games. These are announced at the beginning of the show, between rounds and either side of a commercial break. Viewers enter by calling a premium rate telephone number, and one caller is randomly selected to play the game. Normally, three phone-in games are played in the course of the show, for increasing amounts of prize money. Usually the prizes are £250, £500 and £1000 respectively; they are often increased to £500, £750 and £1000 on Fridays. There are also occasional "double days" on which the prizes are twice the usual amounts.

The first kind of phone-in game is a Scramble puzzle, which is usually played only for the £250 games. The second kind is presented as a pyramid of words similar to the final round, but filled in except for one line in which only the letter added from the row above is given. The presenters often give clues to the words to aid those unable to work it out.

A recent addition is a fourth phone-in game announced at the end of the show and again during the commercial breaks of the following programme. This is often a Scramble puzzle, but for a prize of £1000.