Plot twists spin storylines in unexpected ways. A good plot twist will leave the player staring in disbelief at what they're seeing, but more subtle plot twists can be effective as well. The plot twist can be used to keep the story fresh and interesting - this compels the gamer to keep on playing to find out what happens next. For example: The player character wakes up with amnesia, tasked with fighting some evil leader who has gone missing. Players then find out that they themselves were the evil leader.
The plot twist can be dangerous if not used correctly. They must fit in with the story and make sense. A misused plot twist can confuse, frustrate, or reveal embarrassing plot holes. Overuse of plot twists can come at the expense of a coherent and compelling story.