Combat in Dead State is turn based. You press a button when your turn is done, there is no timer.
The player has full control of the party. However depending on their personality, perks the player may have, or if they are panicking or not, the ally may not accept the player's orders.
If an AI in the game targets an enemy with a ranged weapon, their chance to-hit is calculated for that enemy. If they miss, it does not hit the target next to it, it just misses. There are a few weapons that could be dangerous if a crowd is standing around when they go off, but for the most part weapons are specifically targeted at whatever the cursor is on. You can target an ally for those special "they had a terrible accident" cases when you need to get rid of them.
Allies will only use what you give them. They won't just grab stuff out of inventory for no reason. You are responsible for assigning them armor, weapons, accessories, and other items, though they may have preferences. To give an item to an ally either switch to that ally and pick up the item, or right-click the ally and left-click when you see the 'backpack icon' to bring up the inventory trade screen. The inventory trade screen may not be brought up while in combat mode, so plan accordingly.
To swap positions with another ally, you must be directly adjacent to that ally. Right-click on the ally until the 'switch places icon' (two hands) comes up, and then left-click. This action will take 2AP while in combat.
Allies may break rank and charge the enemy. The player can either try to call them back next turn, assist them, or leave them to their fate.
Certain attacks target limbs or other body parts, but you can't target any body part with any attack. There won't be dismembering for human characters, just for zombies.
There are crippling injuries that take time to heal, but there are no permanent injuries. Putting injured characters in the infirmary and assigning characters with medical training to the room will speed up recovery.
There are temporary and persistent status effects. Temporary effects will wear off in a few turns, while persistent effects need time/medical personnel to heal. Examples of persistent status effects would be burns (reduced to-hit), major wounds (HP dropped to a critical state), and arm sprain (doubles AP cost of everything but movement).
There are a few non-lethal weapons, but we don't have any kind of information extraction system. Mostly you use non-lethal to leave a live target as bait for zombies.
A certain amount will heal naturally per day or can be treated with medical items. All healing can be sped up by assigning personnel to an infirmary.
Move order (initiative) for allies and enemies is determined by the Perception stat. After that, Agility is used for ties. PC always wins a tie. Perks influence initiative too. Zombies tend to go last, unless they initiated combat.
Humans can't see as well at night. Zombies have no special behavior, but are also able to see less during the night. Night works more toward the zombies advantage, since they are still attracted to sound and the party is more likely to stumble into them.
There are breakable doors, but hitting them creates noise. Zombies can bash through doors.
There is no fire mechanic, but there are thrown weapons that can be used to set an area on fire temporarily. Zombies that are on fire will remain on fire until they die. They go out when they die.
There is no weather.
NPCs have dialogue for combat situations.
The NPCs have a threshold for damage and Horror, and only after they reach that threshold will there be a chance to panic, with that chance improving each turn until either they panic or circumstances change enough to no longer make them worry. Most likely they will try to alert you if the situation is bad enough for them to become panicked. As a player, you won't know the actual threshold of your allies, though you will know if any have perks that make them never panic.
Panic is caused in two different ways – from reaching a damage threshold or from Horror, their tolerance for the presence of zombies. Depending on the individual, some will try to get away from danger if they lose too much health, while others will fight until they're bleeding out on the ground. The best way to counter damage-based Panic is too keep an eye on ally health and patch them up regularly – you’ll probably get a feel for how much punishment they can take after a few combat situations.
If someone panics often, they either need to get more experience against zombies, or possibly they're just not going to be good at combat. Fortunately, there are many other uses for allies who aren't good at combat. Most of their responsiveness or willingness to cooperate are already dictated by their Mood. That's true for allies with friends and family in the Shelter too, since they are more likely to be better off mentally if their loved ones are okay.
If someone is panicking, all you can do is try to eliminate the source of their panic. If they are wounded, try to heal them. If they are terrified, try to kill some zombies around them. If they're being shot at, try to draw fire or eliminate the shooters. They may continue to be panicked for a turn or two, but with the threat gone, you won't have to worry about them panicking again.
Anything not in your secondary weapon slot will be in your inventory and there is an AP cost for digging through your inventory during combat
Humans can get infected by a zombie when they are low on HP. It is assumed their armor/physical toughness is compromised and there is a chance that a zombie bite will now find its way to bare flesh.
Zombies will grapple. It's one of their major attacks. A zombie’s grapple or attacks can occasionally cause the player to get knocked down (knockdown is also a result of certain types of melee/thrown weapon attacks). If an NPC gets grappled by a zombie, they have to spend AP to break the grapple at the start of their turn. This isn't such a problem when there are one or two zombies around, but when surrounded, you have a lot fewer AP to clear a path out of the mob. If zombies knock someone down (on their back) all the surrounding zombies have a special attack they can use now that the squishy parts are more easy to get to through armor.
Currently, you can't crouch, go prone, or sidestep and cover is mostly about staying out of the lines of sight
A lot of the strategy comes from the different weapon types, how you employ them, how you use thrown items (like noisemakers), where you choose to engage enemies, how much your allies compliment your style, and how you pick your battles.
Armor, is up to personal preference/need more than it is a linear boost to the defense rating. Armors have a basic defense rating which is subtracted directly from damage. Most sets also have a resistance to certain kinds of attack, which reduces the attack damage by a certain percentage. Resistance bonus is taken off first, and then reduced by the damage resistance of the armor.