The imposters are what they call an unknown species that keeps killing off groups. As the imposter you job is to wipe out the whole group before they figure out it is you. You will have fake tasks that won't count to anything. But when you do a fake task it will show that you did the task under your name.

If your pms don't work then comment on this page so that I can tell you if one of your characters are the imposter for the round.