One of the most realistic MMORPG I've ever seen is Face of Mankind. For example, if you choose to become a police officer and join the Law Enforcement Department, your objectives include patrolling malls and streets, checking people's criminal record, checking people for possession of drugs, or tasing and arresting criminals. You can also kill people but there's an Internal Investigation division within Law Enforcement Department who can demote, penalise or even fire you from the police force if they find out that you are a crooked cop. Arrested characters are sent to a prison planet which is also guarded by the Law Enforcement Department on the perimeter. Convicts extract minerals (in very small quantities using a mining gun), go for a walk in a prison yard, go to a visiting area to see friends from the outside world. A prison break can occur if a large force overwhelms police forces and succeeds in breaching security gates (hacking device needed / need to play a puzzle game to hack a door). However, if police forces are overwhelmed on a planet, the chief police commissioner can declare martial law on the planet and the government can then send army forces (Freedom Defense Corps) to assist.
If you choose to become a soldier and join the Freedom Defense Corps, you have a different life. A lot of time is spent in training and all kinds of drills. One of the goals in the army is to teach newbies strict military discipline (some people can't stand it and change faction). An officer might fine a private (reduce experience points or credits) even for such a minor thing as not standing in line properly or not saluting a higher ranking member. In the old version of the game FDC were usually crammed on their spaceship doing the training drills there and once in a while they launched off in large forces to overwhelm some planet.
Then there are various clans (mafia, mercenaries, pacifists) an corporations whose members have different gameplay, objectives and hierarchy compared with the army and police forces. Corporations, for example, aim to maximise their profits, mine and produce stuff, compete with other corporations. There are total eight different factions in the game and every player character must belong to one.
There are no NPCs or monsters (there used to be aliens like in the movie "Aliens" on some dark colonies but they were very rare). Everything is ran, planned and organised by players. Experiene points are needed only in the beginning to get promotions for initial ranks within your faction. If you want to advance in the ranks and become the leader of your whole faction (e.g. the chief police commissioner of the Law Enforcement Department or the general of Freedom Defense Corps), you need to be a very smart, skilful, dedicated and "well-spoken" person in real life. If you reach that level, you will need to plan agendas for your faction, pass orders, directives, instructions to the lower levels of your organisation (e.g. police commissioner to deputy chiefs, detectives etc.) and they will pass it down to the lower ranking members (detectives to constables, street cops etc.). As a chief commissioner you might need to decide on which planet police activity must be increased or decreased, whether you need to declare a martial law somewhere or not, whether to pardon or not some famous criminal, how to support or promote cooperation with the government or some other organisation, how to make your faction more efficient (reorganisation, divisions, units etc.) and so on. If you are the kingpin of the Brotherhood of Shadows (a criminal faction), you might influence what/where/how your faction produces and distributes drugs, whether you need to arrange a prison break for someone or not, which planet to try to take under your control etc.
The game plays as a first person shooter. There's a cone of fire which widens as you walk or run or narrows if you stand or crouch. The cone of fire is bigger (less accuracy) with heavier weapons, narrower with smaller fire-arms and a sniper rifle. There's a knife, taser, 3-4 pistols, 2-3 machine guns, 1-2 rifles, 1-3 types of bullets for each weapon, 3-4 grenades, 3 medikits, biocell, 3 types of "generic" armor and 6 types of "faction" armor for each faction (there are separate items for head, legs, arms and torso, 9 types of each), 5-6 implants, a lot of different types of drugs in the game (and some trivial stuff like different types of sunglasses, food, clothes). There are also a lot of different types of raw materials and component materials needed for production of items. Every item in the game has to be manufactured by someone. In order to produce an item, you need to have a production module (so one player can usually afford to specialise in producing only 1-10 types of items).