This improv game is in the following improv game categories:
Participants can mirror who ever they want to in the circle and shouldn't let the person they're mirroring guess that they are being mirrored.
Alternatively, one player gets out of the room and waits outside while somebody is designated in the circle to be copied by all the other members of the circle. The player waiting outside is called back in and has to guess, by observing the circle, who is originating the movements that everyone else is copying.