As some of you know the Trials of Osiris event has to with or even takes place on said planet. Its been said in-game that this planet has been turned to a machine. I for one am expecting something that resembles The Deathstar or better yet Cybertron from Transformers. Venus and Mars has their share of Vex ruins but Mercury is supposed to be all machine, being a small planet i can see this being easy for them. Also Im guessing that most if not all zones will be inside the planet rather than the surface due to intense heat and brightness. Going into parts of the planet exposed to the sun could result in a burning loss of health and eventually death, the planets rotation could play a roll in it as well. The planet itself could be aware of your presense and could try to hinder your progress through the map. I know that we get could have none of this and it still be enjoyable but this would make the burning planet of Mercury the coolest planet in the game.