Phased Real-Time Combat for Call of Cthulhu

Combat in Call of Cthulhu is supposed to be dangerous, chaotic, and fast-pacedThis ties in very well with other themes of the game: investigators being just normal people thrown into dire situations over their heads; the mythos being a terrible threat which you can rarely confront directly and live; and for combat to be almost a failure state, when investigation and other more subtle techniques fail.

. Investigators aren’t supposed to wade through fields of blood hacking down dozens of enemies like in some RPGs.

However, while the standard combat system does manage to feel dangerousInvestigators have low health relative to even mundane weapons: a single lucky bullet can kill someone outright.

, I don’t think it manages to feel fast-paced or chaotic. I’ve found combats to be a drag at times, with a short amount of in-game time taking a much larger amount of out-of-game time to resolve.

Call of Cthulhu uses a pretty standard combat system: combat is divided into rounds, in each round there is an unambiguous order in which each combatant gets to act, and after each combatant acts another round begins with (probably) the same order. This is great for D&D-style tactical combat, as it allows the players to treat the fight almost like a boardgame, putting their effort into figuring out the optimal moves. I don’t think it works so well if combat is supposed to feel chaotic though.

This memo does away with the strict turn order, and brings chaos back to combat. The system is based on Phased Real-Time Combat.

This has not been play-tested yet.

Round structure

A round is broken down into these phases:

  1. Hints: Keeper hints at what the enemies are doing
  2. Orders: Players declare their actions
  3. Fast spells: Cast instantaneous spells
  4. Fast actions: Fire readied guns and act with 100 or more DEX
  5. Slow actions: Other attacks, manoeuvres, or skill checks
  6. Movement: Movement and fleeing
  7. Slow spells: Cast non-instantaneous spells

All actions resolved in the same phase conceptually happen at the same time.

The Keeper’s Rulebook lists the following actions which are suitable to perform on your turn during combat:

  • Initiating an attack using a suitable combat skillSome monsters can perform multiple attacks in a single round.

  • Performing a fighting manoeuvre.
  • Fleeing.
  • Casting a spell.
  • Performing some other action requiring time and perhaps a dice roll, such as picking a lock.

Additionally, you can choose to wait for another combatant to act before performing your action if your action is in the same or an earlier phase.

Action resolution

In each resolution phase, there will generally be clear groups of actions which have to be resolved together and which can be resolved independently of any other groups. For example, if there are four combatants engaged in melee as two pairs, each pair can be resolved independently.

Even within a group of combatants all fighting each other, order only matters in some situations. For example, all attack rolls can be resolved simultaneously, unless a combatant will be incapacitated or killed, in which case their attack and the killing blow need to be resolved in order.

Where order matters, combatants make an opposed DEX check. If there is a tie:

  • PC vs NPC: the PC wins.
  • Otherwise: flip a coin.

Concentration and interruption: certain actions require the character performing them to have uninterrupted concentration. For example, casting a non-instantaneous spell requires the character to maintain concentration between declaring the spell and casting it. If a character making such an action is successfully attacked, grappled, or otherwise interrupted, the effect does not take place.


I think this approach has a few big advantages over the standard round structure:

More closely matches the fiction: with a sequential round structure, we’re often told that things are really happening at the same time in the fiction, but I think that is basically impossible to justify. You know everything that happened before your turn in the round, so you’re almost certainly going to base your move on that. But if things are happening simultaneously, you shouldn’t be able to do that.

To use the needlessly complex-sounding jargon term, this is an example of ludonarrative dissonance: the narrative and the mechanics are in conflict.

Less disjointed: if everyone acts in turn order, a round of combat just becomes a monotonous recital of disjointed actions, jumping between all the combatants. Have you ever read a combat scene in a book, or seen one in a film, where it just shows what everyone is doing, one after the other? No! The narrative jumps between groups of characters, showing their part of the fight as its own miniature scene before jumping to another group.

By focusing on these small integrated scenes, the combat as a whole feels faster-paced.

More chaotic: because you have a much narrower view of what’s going on—you know the orders the PCs say, but only get hints of what the NPCs plan—it’s much harder to strategise like you would in a D&D-style tactical combat minigame. The fight becomes much more unpredictable and chaotic, as you have to take into account the fact that: (a) you don’t have perfect knowledge of what many of the other combatants are doing by the time it rolls around to your turn; and (b) you don’t even know the order in which your part of the fight is going to resolve.