Performance game at Equinox 70, by Henri Picciotto and NeilFred Picciotto (Hot and Renfield)
Chain Reaction was first played at a very early Equinox Party, we're not sure which one. It spawned a number of variants in the years that followed. For the 70th, we re-played the original game plus one variant, and we used a legal pad of answer words that Henri still had from decades ago (skipping over a few answers that were very "of their time").
Rules for the original game:
The host prepares words/phrases to be clued, written or printed large enough for the whole room to be able to read them. Each round has two cluers and one guesser, and runs for one minute. The guesser stands with their back to the stage, where the host holds up the answer words, visible to the cluers and the audience. When the guesser guesses the answer, a new answer word is revealed and play continues, until the timer runs out.
To form their clue, the two cluers take turns saying one word at a time, and as they do so, they must form a grammatically-correct question. It is recommended to start with the word "what". For example, if the answer word was "the Bay Bridge", the cluers might say:
Cluer 1: What
Cluer 2: structure
C1: connects
C2: Oakland
C1: to
C2: San
C1: Francisco
The guesser of course can jump in anytime to guess an answer, even if the clue is not yet a complete sentence. On the other hand if the cluers reach the end of the intended sentence and the guesser still doesn't know, they can continue the sentence with "and"...
Variant: "Blind Chain Reaction"
This time, instead of two cluers and a guesser, each round has just one cluer and one guesser, and the guesser must participate in alternating words to form a grammatical question, even though they don't know what the question is trying ask.
In both versions (but especially in the "Blind" version), it's worth noting that while the question is required to be grammatically correct, there is no requirement that the intended answer word actually needs to be a correct answer to the question asked.