Timer Imposter is the imposter game played on a stopwatch instead of a word. Everyone is shown the same target time except one player, who is dealt IMPOSTER and never learns the number. Then every player runs the timer blind while the rest of the group listens, and you work out who was faking.
You will also see it called the imposter timer game, or the stopwatch imposter game. Same thing.
How is it different from the normal Imposter game?
In our word Imposter game, everyone gets the same secret word except the faker, and you take turns giving a one-word clue. Here the secret is a length of time, and your clue is a duration: you start and stop a hidden stopwatch, and all anyone hears is the beep at the start and the click at the stop. Same social deduction, no words at all.
How many players do you need?
Three at minimum, up to twelve, on one phone passed around. Two does not work, because there is nobody to compare the imposter against.
Do you need anything else?
No. It is free, there is no signup, and it runs in the browser. If you want the plain version without a faker, that is the Timer Game, where everyone knows the target and closest wins.