What Is Simultaneous Combat in a Tabletop RPG?
The fighter sees the ogre and charges.
Across the room, an archer sees the same ogre and draws an arrow. The wizard begins a spell. The rogue moves toward the creature's unprotected side.
The ogre isn't waiting for any of them. It charges too.
All five characters are doing something during the same few seconds. But that doesn't mean all five actions will finish at exactly the same instant. The arrow may reach the ogre before the fighter does. The two charging combatants may meet while the wizard is still casting. The rogue may still be moving when the fighter's sword comes down.
Everything is happening at once.
Everything is not happening at the same time.
That distinction is the key to simultaneous combat.
The Traffic Intersection Problem
Imagine standing at a busy intersection.
Cars are moving north and south. Pedestrians are crossing. Someone is turning right. A cyclist is approaching the corner. Another car is slowing down.
If you took a photograph, you'd see all of those things happening at once.
But they didn't all begin at the same moment, and they won't all finish together.
That's closer to what we mean by simultaneous combat.
The battlefield isn't a collection of characters frozen in place until the game gives each one permission to move. It's a collection of actions already in progress.
One character may be halfway across the room while another is raising a weapon. Someone else may be preparing a spell. An enemy may already be retreating.
The challenge for a tabletop RPG is figuring out how to represent all of that without requiring the Game Master to become an air-traffic controller.
That's where things can get messy.
“I Was Already Moving!”
Consider a simple situation.
A fighter is running toward a goblin. At the same time, the goblin is running toward a doorway.
Does the fighter reach the goblin before it escapes?
In a traditional turn structure, the answer may depend largely on whose turn comes first. If the fighter acts first, the fighter moves and attacks. If the goblin acts first, perhaps it reaches the doorway.
That's easy to resolve.
But it can create some strange moments.
“I was already chasing him!”
Yes.
In the imagined battle, you probably were.
The rules simply had to place those overlapping actions into an order so we could resolve them.
Simultaneous combat approaches the same situation differently. Instead of asking which character gets to perform their entire action first, we can look at what both characters are doing during the same period of time.
The fighter is running. The goblin is running.
Now their speed, distance, circumstances, and what each is trying to accomplish can actually matter. Neither character needs to freeze while the other moves.
Actions Have Pieces
This becomes much easier when we stop treating an action as something that appears fully formed. Think about attacking someone with a sword.
You may need to move into range, position yourself, make the attack, recover, and decide what comes next. We can casually describe all of that as: “I attack the goblin.” But there's quite a bit happening inside those four words.
Mayhem breaks actions into Links. Those Links can connect to create Chains.
That matters because the Links don't exist in isolation from everything else happening on the battlefield.
While one character is moving through a Link, someone else may be moving through another. A third may be doing something entirely different.
Those Chains are progressing alongside one another.
Now simultaneous combat doesn't require us to say that the fighter's entire attack, the rogue's entire movement, and the wizard's entire spell all occur at the same instant.
They don't. Their Links overlap in time. That's a much more manageable idea.
When the Chains Meet
This is where simultaneous combat becomes interesting.
Suppose the fighter begins moving toward an enemy while the archer prepares a shot. The fighter hasn't reached the enemy yet. The archer fires. The arrow reaches the enemy before the fighter does.
Something happens. Maybe the arrow misses and nothing changes.
Maybe it hits and injures the enemy.
Maybe the enemy reacts by moving.
Maybe the hit is serious enough to completely change what the fighter was planning to do.
The fighter's Chain hasn't disappeared just because the archer acted.
It's still happening.
But now the circumstances surrounding it have changed.
That's important because actions in a real fight aren't independent little scenes.
They interfere with one another. Sometimes they help. Sometimes they ruin everything.
“Don't Cast That!”
Now put the wizard back into the battle.
The wizard begins preparing something spectacular. The fighter sees an enemy and charges. Unfortunately, the fighter is moving directly toward the area where the wizard intends to place the spell.
In a turn-based game, the order may make the situation easy. Perhaps the spell happens before the fighter moves, or the fighter moves before the wizard chooses a target.
But what if both were already acting?
Now we have something much closer to the confusion of an actual battle.
The wizard can continue. That may be a terrible idea.
The wizard can change plans.
The fighter might realize what's happening and stop.
Someone might shout a warning.
What began as two independent decisions has become one shared problem.
This is one of the things simultaneous combat can do particularly well. It gives players reasons to care about what other players are doing because their actions can directly affect yours before yours is finished.
The other player isn't merely taking their action while you wait. They're changing your situation.
Segments Give Us a Clock
Of course, we still need a way to keep all of this from becoming:
“I did that before you did!”
“No you didn't!”
“Yes I did!”
That's where Segments become useful.
Segments give overlapping actions a shared sense of time. They help us understand how far different actions have progressed without requiring everyone to finish one complete action before someone else can begin.
Think of them less as tiny turns and more as marks on the same clock.
The fighter's Chain is progressing.
The rogue's Chain is progressing.
The enemy is doing something too.
The wizard's spell is progressing.
A Segment helps us see where those actions are relative to one another.
That gives us places where actions can meet.
The arrow arrives.
The fighter reaches the enemy.
The spell finishes.
The door closes.
Something happens, and the situation changes.
Then everything already in motion has to deal with the new situation.
The Battle Doesn't Reset
This may be one of the biggest differences in how simultaneous combat feels.
There isn't a clean reset after everyone has acted.
The fighter doesn't return to a neutral state because a round ended. The rogue doesn't teleport back to the beginning of an action. The wizard's unfinished work doesn't vanish.
Everything carries forward.
If you're running, you're running.
If you're casting, you're casting.
If you're defending yourself against an angry ogre, you're probably still extremely interested in the angry ogre. And if something happens halfway through what you were trying to do, you may need to deal with it. That makes actions feel connected.
One thing leads into another instead of each action existing as its own little island.
Chains reinforce that idea because what you're doing now can lead naturally into what you do next.
The battle becomes a flow of connected decisions.
Simultaneous Doesn't Mean Faster at Any Cost
You might assume the whole point of simultaneous combat is speed. Speed matters. We've already talked about how much RPG combat time can disappear into waiting.
But making everyone act at once merely to finish combat faster would miss the more interesting benefit. Simultaneous combat can make other people's actions matter to you.
While the rogue is moving, the fighter may create an opening. While the wizard is casting, the enemy may do something that makes the original target a terrible choice. While an archer prepares a shot, another Contender may suddenly block the line of fire.
That means watching the battle isn't something you do just to be polite while another player acts. You're gathering information.
Something happening right now may change what you're already doing.
That's engagement created by the situation rather than by waiting for the Game Master to call your name.
What About Rounds?
Simultaneous action also doesn't mean Mayhem abandons time.
A battle still takes place over measurable periods. Moments and Rounds let us keep track of short stretches of time, and turns remain useful outside the immediate combat scale. Spells and other effects still have durations. Things that started before combat can continue during it, and things begun during combat can outlast it.
The clock never disappeared. We simply stopped handing pieces of it to the combatants one at a time. That's an important distinction.
A Round can tell us that time has passed without meaning that everyone had to take one conventional combat turn during that Round.
The Round belongs to the battle. Not to the queue.
Everyone Is in the Same Fight
Go back to our ogre.
The fighter is charging.
The archer is firing.
The rogue is moving.
The wizard is casting.
The ogre is charging back.
We don't need to pretend all five actions finish simultaneously.
We only need to recognize that all five actions can be in progress simultaneously.
Then we let time, Links, Chains, Segments, and the events of the battle tell us when those actions intersect.
The arrow may arrive first. Perhaps it hits. Now the ogre reacts.
That changes the fighter's approach. The rogue sees the opening. The wizard sees something entirely different. Nobody's action happened in a vacuum.
That's the part of simultaneous combat that interests us most.
It's not about making five people roll dice at the same time.
It's about creating a battlefield where five people can be doing something at the same time—and where what one of them does can change what happens to everyone else.
The battle isn't waiting for anyone.
It's already moving.
Next from the Engine Room
Of course, there's a problem.
Once we stop putting everyone into a neat combat order, how do we make sure the system stays fair?
Who gets the advantage when two actions collide? What stops the fastest player—or the loudest one—from dominating the fight? And if the battle itself can change who has the advantage, how do we keep track of that without simply rebuilding initiative under another name?
Removing initiative is easy.
Replacing the job it was doing is the hard part.
That's where we're going next.