Though the game does have a tutorial, it doesn't do that job very well (atleast in my opinion),
and seeing how there aren't any other guides yet about the gameplay, i thought about making one myself, again, just like in my first guide, if you have played this game for quite a while, you won't learn anything new here.
(Note: this guide assumes you have played the tutorial so you atleast know the basics of the game)

When you pick up a weapon it will have two important stats: MFK and Damage
When you make a kill with a weapon, you will get the amount of money that the MFK on that weapon shows, every round the weapons that did not get used will be worth more MFK, this is why you don't want to use the same weapon as everyone else.



When two players use the same weapon, the first one to get a kill with it (being the target ofcourse) will get the full money, players after that will only gain half of that money that round (for example, if MFK is 2000 then the first kill would be 2000, second would be 1000, third would be 500, etc)
After each round all weapons that were used will be reset to a total of 100 MFK
Although i don't have direct numbers about the "damage" stat, as far as i can tell:
2-3 stars = 3 hit kill
4 stars = 2 hit kill
5 stars = 1 hit kill

An exception to this rule is the syringe item, which shows 1 star but will instantly kill over time
There is also a weapon that deals no damage and has no MFK stat, the sleeping syringe, when used the target will go to sleep in around 2-3 seconds (same as when a player ignores the sleep stat), this can allow for a very easy kill.
(green = kill / orange = sleep)

This is the system that can create ragequits when you have no idea how to avoid it, just like the cops and cameras, this system will get you into jail.

When you are being watched by two players, a little eye will appear in the bottom right, this will fill up when you hold a weapon, so unlike the cams and cops, it isn't instant.
But, the more people that watch you, the faster it goes (so when six or more players are watching you, it'll be almost instant)
This can be very hard to avoid on high populated servers.

If you do get spotted, you will get a fine (depending on the amount and what kind of weapons you had on you) and you will be thrown into jail.
As bad as this sounds, it can also bring positives, because you can do every need in the jail while being almost save from your killer.

You're not 100% safe because if your killer goes into jail with you, he could potentially find a shank in one of the little boxes next to the beds (or between books, the spawn locations depend on the map),outside of the jail there are also some windows looking in with no security around them, so you can still be shot by your killer (again, depends on the map, but this is fairly common).
A good strategy when your target is in the jail is to just wait outside of it, as the person coming from jail will have NO weapons at all (unless they found a shank)

Geoarrge:
"Non-weapon" weapons like the walking stick or umbrella will be returned after coming out of jail.
Thanks for the tip Geoarrge !

The clinic is a VERY important room which gets no mentioning in the ingame tutorial at all.
In here you can heal up and find two very good items (the green and orange syringe i mentioned at the "weapons" tab)





When you talk to the lady behind the desk she can offer you multiple things, she can:
-Be talked to (decreasing your social need)
-Heal you for a little (at the cost of 250)
-heal you for alot (at the cost of 500)

As of now, there is no way to tell how much health you have (atleast as far as i know)
but you can only get healed if you took any damage in this life.

(EDIT: The more your reticule goes up and down, the more damage you have taken, thus the lower HP you have, thanks DANGERMOUSE!)

When you run down the hall, you will find two rooms, the psychiatrist and the doctor, both rooms can contain syringes and scalpels in the desks, but the doctor's room has a higher chance of having these, on some maps there are also some trashcans down the hall, these can also contain syringe's (and a very rare chance on scalpels)
Both the syringe and the scalpel make amazing weapons because of their damage and they can only be found in these room, making them very rare, thus increasing the MFK.

You can also find two bags which allow you to do the "toilet" need, i DO NOT recommend using these items as the hygiene need goes up like crazy,

(NOTE: None of the staff in the clinic care about you, so another player can just walk in and kill you without going to jail if there's no cams around)

Good luck and have fun
-Redey59

Edit1: Old guide, but still had my name on it so decided to fix some grammar and spelling