Two three-member teams competed. Each consisted of two celebrities and a contestant. Order of turn: celeb #1, player, celeb #2, repeat.
The board opened to reveal eight blank spaces. Only the top and bottom words of the chain were revealed in their entirety.
The team of challengers went first. On a member's turn, s/he could ask for the first (or next) letter below the revealed top word or above the revealed bottom word; the letter revealed. If the member correctly guesses the word, it is revealed completely and the team is awarded one point per letter; if it was a double score word (denoted by a "+"), value was two points per. Otherwise, control of the chain goes to the other team.
Game continues until one team scores 50 points. If no one reaches 50 by the time all eight words are revealed, they play another chain. The player of the winning team receeves $250 (later changed to $100), and goes to the bonus game.
The original bonus game went like this : The player was given 60 seconds to turn $1 into $10,000. The object was to give eight correct answers in a minutes. Every time a player answered correctly, half of a zero lit up on a scoreboard. Every other right answer fully lit up a zero. Deemed too hard to win, this version of the bonus round lasted only a week.
After the first week, the mission was nine in 90 building on $0 and working to $10,000. The first correct answer was worth $1. Each of the next three added a full zero. At $1,000, each correct answer was worth an additional $1,000. At $5,000, the ninth and final correct answer doubled the money to $10,000. Assuming you answered more than half of the celebs' questions correctly, this was a bit too easy to gain a very respectable cash prize.
The third version of the bonus round went like this : The object of the bonus game is to turn $0 into $10,000 in 90 seconds. One- or two-word answers are displayed on the celebrities' secret screens. The celebrities alternate one word at a time building on a likely question to that answer. To put the proverbial question mark on the question, one player sounds the bell on the table and the player responds. If s/he responds correctly, s/he is awarded $100. Ten correct answers in 90 seconds pays $10,000.
The final version of the bonus round went like this : The object of the bonus game is to turn $100 into $10,000 in 90 seconds. One- or two-word answers are displayed on the celebrities' secret screens. The celebrities alternate one word at a time building on a likely question to that answer. To put the proverbial question mark on the question, one player sounds the bell on the table and the player responds. If s/he responds correctly, s/he is awarded $100. Nine correct answers in 90 seconds pays $10,000.
The "New Chain Reaction" (which debuted in 1986 in first-run syndication) played the same as the 1980 version except that there were no celebrities, and there were two players per team. Usually the teams consisted of married couples. A new feature in this version was a "pass or play" option. Each word in the first chain was worth 10 points (except for the final word, which was worth double), in the second chain 20 points, and in the third chain 30 points. First team to 200 won the game and played for a jackpot that began at $3000 (later $2000) and increased by $1000 until won.
In the bonus round, a standard chain was shown to the players, and the players alternated guessing the words. If a contestant answered incorrectly, a letter would be added to the word, and they 'lost' a letter from their tally. The tally began at 9 letters.
In January 1991, the show became the "$40,000 Chain Reaction". The team element was eliminated and one contestant played the game in an attempt to be the weekly champ and win $7500. The bonus round was a three word chain and offered $300 if a contestant solved the chain with one letter in the middle word, $200 with two letters revealed, and $100 with three letters revealed.
The top players came back to play in a tournament, and the winner of the finals (500 points were needed to win!) won $40,000. The finals were held on the final episode in December 1991.
Blake Emmons was the original host of the "New Chain Reaction", but he was replaced during the first season by veteran emcee Geoff Edwards (of "Treasure Hunt" and "Starcade"). Coincidentally, Geoff Edwards substituted for Bill Cullen for one week of the original series while Cullen substituted for an ill Allen Ludden on "Password Plus".