The Butterfly of Doom is a Time Travel Trope, named for the Butterfly Effect of Chaos Theory (which, itself, is the notion that the flapping of the wings of a butterfly on one continent has some impact on the weather patterns of another continent). In regards to Time Travel, the notion becomes a bit more sinister. It is common in time travel tales that even the slightest change to history can have massive unexpected impact on the future, almost always for the negative. For every McFly family happy ending, there's at least a handful of tales more in keeping with Ray Bradbury's A Sound Of Thunder, where the death of one insect in the time of the dinosaurs puts a Fascist in the White House.
Game and Story Use
- There's plenty of opportunity for this in time travel RPGs, but the GM has to be a little careful. Most players would get very upset if the causality link were as flimsy as what's presented in A Sound Of Thunder. If you ever plan to do this sort of thing, it'd be a good idea to establish it early so the players are forewarned.
- In a Paranoia game, an experimental time machine could have ridiculously random Butterfly of Doom affects. Since the GM being capricious and vindictive is a staple element of the setting, the players would likely take it in stride.