“ Game Cliche 2.
Upon learning about 'the five ancient jewels' or 'the nine legendary icons' or whatever, you can be quite confident that Saving the World will require you to go out and find every last one of them.”
“ The PCs are accosted in a major city containing at least one famous fortuneteller / prophet of the future. They are informed that their as-yet-unborn child will (insert terrible evil), and that, although they are very sorry, the PC must be executed to keep this from happening.”