>>674382
Well, there is an infoscreen in the game for it, F1.
But I can give you a basic rundown.
Everyone is on their own at the beginning. After a few moments, a murderer is picked out of random, and the rest of the players are deemed innocents. The murderer's job is, you guessed it, to kill everyone. The murderer immediately gains an arsenal of traps and supplies they can use to hunt everyone down, such as a gas bomb, or traps that shoot people when ran past, or smoke bombs. The gas is the most useful, and is best at breaking up groups of innocents huddled together closely. As the murd, you also gain access to the hidey holes in the walls, which are marked by exclamation points. These are pathways that only the murd can enter, and are used for hiding, laying low, resupplies, and traveling around the map undetected.
The innocents play another game. They have to find out who the murderer is, and take them out. There are three ways to know: the player has a knife in his hands (on the sprites), uses or drops a trap, or enters a hidey hole. There is a variety of weapons laying around the map that can be used, as well as guns and ammo. The murderer can use them too, however. If you attack an innocent and kill them, you are marked as a traitor with a yellow aura. You basically have to make allies and work together to fight the killer.
Sorry if that was a tad convuluted, but i just typed it up quickly while the hot water for the shower comes on.