On Monday we talked a bit about encumberance, how it worked in reality, and how it works in most RPGs. Today I want to bring that discussion to combat. RPGs and the gamers who play them are funny creatures. We tend to get hung up on realism, meanwhile we're comfortable with a turn based combat system - as much out of necessity as anything - and all the things that that system allows to happen. The distinctions between what happens in the rudimentary simulation a table top RPG provides, and say literature or reality, is also important to understand as both a player and a GM, if only to manage expectations.
Wait Your Turn
The biggest difference between table top and "the real world" is that in table top you have to wait your turn to go. This has benefits and hindrances, but ultimately it means that combats in RPGs are more tactical than most fights you'd see in real life with more consideration going into moves. This happens because in RPGs there is detachment (you're not actually in the fight) and because while a combat round may be 6 seconds in game time, you'd be hard pressed to resolve a single attack in 6 seconds in real life.
Because of this, Joe gets to see what Sarah, Linda, Carl, and Mike all did - and how it worked out - before deciding what to do with his turn. He doesn't waste time or movement going towards an enemy that was standing when the turn began but was felled by an ally. He doesn't pause to see if he should go back and help Toby who fell last round because Mike is already on it. He just does what the player feels is the tactically optimal move (or most in character move) and does it.
This is important to consider as a GM because it means it can be next to impossible to mentally overwhelm your players with things needing to happen, because there is plenty of time to parse it all out. It also makes a losing fight feel terrible because there's nothing you can do but watch as the enemy goes through his 5 attacks, even though the first one already dropped someone.
Who Cares About Reach?
In the real world reach is one of the most potent things to consider when selecting a weapon. There is a reason swords were seen as more of a last resort weapon by most cultures that used them. To use a sword (unless it's a great sword) you have to get really close to your opponent, and that means your opponent is really close to you, and that's bad. Instead, most cultures used weapons with reach. There were weapons like bows and crossbows (more on them later), but also spears, pole axes, and other polearms.
With a spear in hand you could keep the enemy more than six feet away, poking at them and never letting them near you. You were safe at one end of your stick, and they were in danger at the other end. Entire chunks of military strategy are based on this fact, and it's why the front lines, and main forces, of armies were often units with spears. They let you keep your people alive while killing the other.
In RPGs this isn't so much the case though. The advantages of reach are usually that you can attack a square earlier on the battle mat - or over an ally. D&D 3 and 3.5 had attacks of opportunity for when you moved out of any threatened square, and so a spear could poke you for free just for engaging. However, this didn't really stop the person from closing in (unless you killed them) it just was some free damage. Still, better than nothing.
Bows, crossbows, and guns also have problems. Game balance usually keeps the melee guys in the fight. Engagement ranges are rarely in the realm of "truly long range." And so what happens? You're 60' away shooting with your bow, and that's great until the enemy is able to move 60' and hit you. Now, if they can't do it in one round yo can fall back to keep your advantage, but if they can? That 60' means very little. Why? Because turn based actions means it doesn't matter that the guy is running down 60' in the open, it's not your turn so you can't shoot him unless you specifically declared a held action to do something like that.
For your game, you need to understand that this changes viable strategies. Archers and ranged characters will be engaged in melee combat unless there is an actual terrain feature (elevation, a pit, etc) that keeps them safe, or characters who keep the bad guys off of them. It's just a fact of life. It also means that certain basic strategies won't work outside of narrative moments or with GM ruling help. That line of pike men isn't going to keep someone with a lower reach weapon from hitting them. At best some of the pikes will get a free attack, but that's hardly the same thing as just flat out denying someone gets into the space.
Injury vs. Hit Points vs. Debilitation
Generally speaking in a real fight if you get tagged once you're going to lose. Maybe the shot kills you. Maybe it just takes you out of the fight. Even if it doesn't, the way your body is likely to react to being injured is going to leave you open to getting hit again and again. Simply put, the more they hit you, the more they will continue to hit you.
Pain, fear of injury, and our own mortality are great assets to keeping fights under "control." the fact there is no second life is why in firefights people don't break cover. And why other people keep their heads down when a weapon not in their control is firing.
In RPGs this isn't the case. First, the player - the one making the choice - has nothing to fear except maybe losing a character. Second, they will feel none of the pain or injury their character may experience. Three, unless the system has wound penalties, taking injuries won't even slow them down and with wound penalties it just makes things harder as opposed to impossible.
Combine this with the limitations of turn based combat, and it is not unusual to see decisions and actions that would never work in the real world but are perfectly viable, if not optimal in games. This includes running down a 30' hallway at a gunman because you can clear the distance in one round and they did a targeted attack instead of suppression fire last round. Real world that guy gets shot and killed. In a game? they close the gap and unload with their melee attacks before the gunner can react.
In short, you need to understand the realities of how your game works when planning out the combats. Especially when you want a flare of realism or a touch of narrative to enter things. Games don't handle those well. The rules the world works on are too different. So be aware of it. Make special rules if you have to. Just don't be caught by surprise if it happens in your game.