Intent is set by clicking the buttons around the interface and determines the context of your actions.
Most of the time when people use the term they mean your help/disarm/grab/harm intent.
For unarmed combat, click here.
Clicking anything or anyone will cause you to use the item you're holding on them. Using an empty hand will make you do something entirely different and is used to interact with many things on the station (e.g. vending machines, computers, picking things up, the list goes on). Experiment!
Click the throw button or press the END key on your keyboard to toggle this. Throwing is 100% accurate and items are seldom harmed by it, so this is a good time saver when putting things away, particularly when the server is lagging and precise movement gets harder. Thrown items can hurt people (the crowbar is an especially damaging projectile) but this is pretty much never a good idea in any combat situation considering how clunky inventory management is. Get an actual ranged weapon and hold onto your melee ones. The main exceptions to this are grenades.
The way to get things out of your hands. Dropping things places things on the tile you are on. You can also use drop to place grenades. Dropping things does not create a message.
This is important, and plays a major role in combat and first aid. What you've set this to can mean the difference between helping the Head of Security up and choking the shit out of him. Along a similar line, not checking to make sure you're using your empty hand even with the correct intent often results in a toolbox to the face. Both of these are surprisingly common occurrences on the station, which is a fair indication that most crewmembers are extremely inept Samaritans, suffering from severe motor retardation, or both. Just make your mistake clear and they'll usually be understanding.
Help, well, helps people. This can mean you're trying to wake someone up, help them stand (both of which require an empty hand), give them CPR (to keep them alive if their status is critical) or medication, if you're compassionately inclined. As stated earlier, trying to help someone with an item equipped will usually just make you beat them with the object, and then have you possibly be beaten by security - also known as being passive-aggressive.
Help intent also allows you to walk through other people instead of bumping into them.
Harm does the most damage and will crit them more quickly than disarm. It's most useful when your victim is already disabled somehow.
Disarm has the highest chance to disable your target by either stunning, weakening or even knocking them unconscious. Disarm tends to be the most useful for ensuring that you survive and come out in top in a duel and it has plenty of offensive use in larger brawls and is used most often. As goes a popular saying, "disarm intent is best intent."
Many actions can be resisted by spamming the resist action, but if they're floored then they can't do shit. Trying to disarm someone with an empty hand will either push them down for about five seconds - buying you precious time to secure your escape, or make them drop their weapon which WILL make them a lot less dangerous and turn the tables if they were carrying something particularly robust, like a circular saw.
Grabbing someone will place a hold on them. Grabbing them again will cause to put them in progressively more advanced holds: passive, aggressive, hands, and neck.
Passive is used to make people follow you but they can break free by simply moving in another direction. Aggressive is essentially the same thing, But the targeted person must try to resist to weaken your hold to a less advanced stage (provided they're not disabled) and escape.
Hands is similar to aggressive, but you can throw them onto tables or across the room. Neck will move them onto the same tile as you, knock them to the ground and cause you to move much slower. While you've placed a hold on someone's neck, they will slowly lose oxygen, but you can press "kill" to speed up the process. You must have an empty hand slot to try and grab someone (try right clicking them and selecting "pull" to get them to follow you)!
Body Part Targeting
Sets what part you want to target when interacting with people. In combat, you want to target their head, torso or legs in order of descending priority, and any armor they're wearing such as hard hats or body vests should be taken into account.
You can aim for the eyes to try to blind them or target the mouth to force-feed things to people provided the item can be physically ingested, such as food, medication and poisons. This is commonly practiced by medical staff trying to give you Bicaridine or Kelotane (doctors on board the station can be somewhat impersonal at times), or an Assistant that was given Mindbreaker Toxin by the chemist. Force-feeding pills to random people makes some people paranoid, so don't get caught doing this.
Works the way you would expect. Running is enormously faster when you don't have a lot of equipment on you and you'll use this setting nearly always. Walking is used to do more precise maneuvering when the server is laggy, or keep you from slipping on wet floors. Note that if space lube was used on the floor you're fucked, not even Galoshes will save you. Running on the outside of the station's hull will make you slip into space more often, so be careful.