This question was inspired by an Arqade question: How do I save a Destiny warp drive?.
The premise is this:
- In order to progress to mission 3 (or 4 etc.) you must complete the second mission. The item you acquired in mission one ( a derelict space ship) led you to mission two wherein you had to find a second item, the warp drive, in order to "leave orbit". This warp drive must be handed over at the end of your second mission, but it's no longer needed because your reward, a new shipcraft, has already one fitted.
The person asking the question on Arqade wondered how to save this item, to avoid losing it, but this is pointless, the fact that the mission was completed is what will give you the ability to progress forward, not that you picked up this item.
Thus, this warp drive is sort of orthogonal to the game. It is an item like any other dummy item added to the end of a mission which in turn you can turn in when you get back to The Tower for some kind of reward. In this regard it is currency, nothing else. "You give me that wrap drive, I give you this ship":
The subsequent ability of the player to "leave orbit" and play on other planets comes from eventually completing enough missions so that missions on the moon becomes available. Even if this warp drive was removed from the game completely the player would be able to do this, once this mission (to recover the warp drive) was completed.
Is there a term for these kind of items?
Items that seem to drive the story forward but are sort of unnecessary, added more like a plot prop to hold in your hands than anything else?
Items given to the player to bring them somewhere, when the real goal was to get the player to that location; the item was just to give them purpose.
Perhaps that is my word; purpose. Or is there a better one?