It's a PRP!
A Player-Run Plot.
A Plot by Players, for Players.
There are a few rules:
A) You've got to be a PGM to run one. To participate, just sign up or ask to join.
B) It's got to be self-contained, or if it needs sequels, make sure the continuity doesn't fuck with Masked continuity.
C) If it's not self-contained, it requires staff approval to make sure your PRP does not involve meteorites slamming into the earth and triggering Inspector Terrible's world-destructo-device into swallowing the universe whole and ending several existences.
The PRP is the core of the game - don't let our biased staff-asses tell you differently. While there most assuredly is an underlying plot you will all more than likely unravel, PRP is just what it sounds like: games by Players, for Players.
Most will not require any specific staff approval, and just need to be posted in the forums to gain the XP - staff will just read over it and you'll get the goods.