Consequences - the game where we write a short story by passing it around a table. Each person takes it in turns to write a line. To make things more interesting, they can only see the one line before theirs. Everything else, including the start of the story, is hidden until the paper is unfolded and the story revealed. Our Sci-fi consequences session began with the phrase "When they first came to Earth, they..." which resulted in all manner of alien invasion scenarios, including two fluffy animal apocalypses, and Donald Trump, though thankfully not in the same story.