Before the change to the most recent format, only two contestants played at a time. The first three rounds were Scramble, Crossfire and Trio, and these were played in two heats, therefore all four contestants played these three rounds. The winner of each heat went into the "semi-final", comprising the rounds Clued Up and Wordstorm. (The "final" is the solo Pyramid game.) Prior to 2005, Wordplay was played instead of Trio, and Wordstorm preceded Clued Up in the semi-final. Wordplay had two differences from the round in the more recent format:

BrainTeaser at five.tv

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:

BrainTeaser was a British game show, first broadcast in 2002, produced by Endemol UK subsidiary Cheetah Productions. BrainTeaser was live, with phone-in viewer puzzles being announced and played during the show in addition to the studio. During its run from 2006 until 7 March 2007, it aired on Five usually between 12:30 and 13:30 Mondays to Fridays, with Alex Lovell as presenter. Until the end of 2005 Lovell rotated presenting duties on a weekly basis with Craig Stevens, Rachel Pierman and Jonny Gould, at different times in the show's history. As of 8 March 2007 the programme has been suspended after it was revealed that the production company had misled viewers regarding winners of the viewer puzzles (entered using a premium rate phone number). Actions included publishing fictional names and presenting a member of the production team as a 'winner'^[1]. Five stated 26 June 2007 the show has been cancelled.

The most recent format ran from November 15 2006 until the show's suspension. In each show, there were four contestants, all of which play the first three rounds. The lowest-scoring contestant is eliminated after each of the third, sixth and eighth rounds, so that only one is left standing for the Pyramid.

The players are shown a word and three possible definitions. The players must buzz in and select the correct one. If the player gets it wrong, he or she is frozen out and that definition is removed. The remaining two players are allowed to buzz in and offer one of the remaining definitions. Often there is a common theme to the definitions given for a word. The principle is similar to Call My Bluff or the board game Balderdash; the words are generally less obscure than those featured in these games, but still unusual enough to challenge most players.

Throughout the show, phone-in viewer puzzles are announced. Viewers enter by calling a premium rate telephone number, and one caller is randomly selected to solve the puzzle. Normally, three viewer puzzles are played in the course of the show, for increasing amounts of prize money. The prize values have varied throughout the show's history; as of 2006 they are usually £500, £1,000 and £2,000 respectively. In recent times there have been many twists to this aspect of the show, including variations in the prize values, having one, two or four puzzles in a show instead of the usual three, and various bonus games (mostly games of chance) by which a caller can win even more money. These are usually themed to an event (e.g. Wimbledon) or a season (e.g. Snow) Two kinds of viewer puzzle are regularly featured:

A game similar to that played on Quizmania and The Mint, in which callers must guess entities with some common theme in order to win money. This is run as a single game throughout the show in which several callers are taken, and is usually titled according to the theme.

In light of the ICSTIS investigation of the use of Premium-rate telephone numbers in various interactive UK television programs, Cheetah productions (a division of Endemol), who make BrainTeaser have admitted that some contestants were fake. Among the allegations revealed to Five and ICSTIS were^[2]:

Five resultantly suspended all shows involving premium rate services, claiming they knew nothing about the scam. However a simple procedure checking daily winners would easily identify the fraudulent activity instantly. Five later admitted that a senior producer at Five was informed by Cheetah that several winners had been fake. Five ignored this advice and continued to broadcast. Avon and Somerset Constabulary are awaiting the reports from ICSTIS and Ofcom to see if they reveal any allegations or evidence of criminal wrongdoing contrary to the Fraud Act 2006. On 26 June 2007, Ofcom handed out a record-breaking fine of £300,000 to Channel 5 for this scam.^[3][4] The Ofcom report found the use of fake winners had begun as an expedient to help the continuity of the live format. As such it was not used frequently until 2007 when with the introduction of the Quickfire viewers quiz time contestants became more pressing. A system was in place that labelled callers Blue, Red or Green. These represented respectively a caller with a correct answer, a caller with a wrong answer or no winner could be found, so a fake name or staff member would be substituted. Endemol claim their original intention was to select a winner after the show; however, this only happened once. Both Channel 5 management and Endemol UK have subsequently apologized.^[5]