Theatre game

The  theatre games tradition is a method of training  actors that was developed in the  20th century by  practitioners such as  Joan Littlewood,  Viola Spolin, Clive Barker,  Keith Johnstone,  Jerzy Grotowski and  Augusto Boal. Theatre games are also commonly used as warm-up exercises for actors before a rehearsal or performance, in the development of  improvisational theatre, and as a  lateral means to rehearse  dramatic material. They are also used in  drama therapy to overcome anxiety by simulating scenarios that would be fear-inducing in real life.

Examples
Small Town Anywhere

Early Days (of a Better Nation)

Gob Squad

Tin Horse Theatre

Resources
Impro: Improvisation and the Theatre, Kieth Johnstone

http://www.bloomsbury.com/us/impro-9780713687019/