Use on-screen instructions.
The crew of a spaceship is trying to survive in the endless expanse of space. In addition to being on guard, they need to keep an eye out for an impostor. If they’re left alone with someone else, they should be aware of empty rooms, and prepare for an attack if that someone is an impostor. Even if it means sabotaging the ship, the Impostor will stop at nothing to kill everyone. His cunning and sneakiness make him a formidable opponent. From behind a ventilation shaft, he can jump out of hiding and attack his victim. If he makes a mistake, it’s hard to find him among the crew. Impostor, wouldn’t you do that?