tension, as in dramatic tension

... and tension because an interactive drama is like a mechanical oscilating sytem (a spring): once intially tensed, that is pushed (or pulled) away from equilibrium, it produces an interesting temporal behavior, with which it is possible to interact...

Dtension, like detention (or détention in French), because a good interactive drama will keep the audience so involved that it will not be able to escape...captivation until captivity!