Like the Mission, the Quest is a moral contract, but it plans to succeed in a more complex objective. The Quest is a longer Mission, with a primary objective and several secondary ones.
To succeed, the quester should complete all the secondary objectives.
Like the Mission, the Quest can be limited in time.
At the implementation level, Quests are a logical sequence of 4 or 5 Missions. They should be linked together, even if the link isn't obvious: they all should work for the same objective. We should avoid a Quest is simply several disparate Missions one after an other.
Quests types:
Sequence of same type Missions (Murder Missions for all a category of people, several Delivery Missions, ...).
Bad trick: Steal Mission(s) + Delivery Mission(s), with or without claim.
Transaction: Recovery Mission(s) + Delivery Mission(s)
Conspiracy: miscellaneous Mission(s) + Rumour Mission(s), to make Mission(s) attributed to somebody else, to send somebody to jail, etc.
Resell: Bought Mission(s) + Delivery Mission(s)
Harassing: Steal Mission(s) and/or Murder Mission(s) and/or Destruction Mission(s) against interests of a person or a group.
Destitution: Conspiracy Quest to obtain a change at some position.
Justice: Investigation Mission(s) + punishment against guilty(ies). (function of cases, Murder Mission(s) or Kidnapping Mission(s) to lead them in a court of justice).
Rivalry: Spying Mission(s) to know about Quests of an enemy group, followed by Counter-Mission.