This makes old scenarios playable because while the occasional scenario will have interesting maps the vast majority are ass when it comes to conveying what you're supposed to do.
I just got finished playing through Marathon Dissent and I definitely could have used this plugin to find the one chip, in the one closet, in the one room, mentioned in the one sentence, in the one terminal, hidden in a hopelessly cluttered map screen and glaciers of terminal text.
Finally, a plugin that ruins mararthon.
This is a plugin for any marathon scenario that will act kind of like GPS navigation when activated. It can show just about any worthwhile objective on the map, and in most cases lead you directly to them.
This is a huge cheat, so it's not really recommended if you want the "true" marathon experience. It's for people that either don't have the patience to navigate through mazes themselves, or for people that just want to make sure they found everything on a given level. It can be very useful for tracking down all secrets.