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A battle screenshot from Final Fantasy IV. The party is lined up vertically on the right and faces Scarmiglione who has summoned three undead on the left. The ATB gage is visible in the battle menu below.

The Active-Time Model

Adapting the ATB System for RPG Play

ATB (or active-time battle) is a time-based alternative to initiative turn order for combat encounters. I fell in love with this mechanic the first time I touched it all those years ago when I first got to play FFVII. Today, I’ve taken a stab at adapting some of the things I love most about it for active-time play in turn-based games.

The ATB System

Originating in Final Fantasy IV, ATB was a system that determined in what order and how often characters could act. Over time, each character’s “ATB Gauge” fills up and, when full, the character is able to take their turn. Gauges usually fill up more quickly for faster characters, meaning a speedy character will be able to act more often.

This was a mechanical development that became a cornerstone for the FF franchise. It has been continuously iterated upon in many subsequent titles over the years and has also been nabbed or mined for inspiration by a slew of other JRPGs/RPGs since. For a brief historical look at the mechanic, check out this Giant Bomb article on the subject.

Why ATB?

I’ve seen others ask “why choose an ATB system over strictly turn-based combat?” ATB notably has a few advantages:

  1. ATB makes a character’s speed more impactful consistently. In most turn-based combat games, a higher speed means you will act first. This can be a decisive factor in combat that only lasts a few rounds (just see the importance of the speed stat in the pokemon franchise), but in games with attrition-based conflict, you’ll only see the benefit of your higher speed stat when turn order decides who gets incapacitated first. With an ATB gauge charging according to your speed every turn, a faster character will both act quicker and also act more often, allowing your investment in the stat to remain important both in fights against an enemy you can strike down immediately and in fights against a bullet sponge boss you’ll be wailing on for a while.
  2. It adds tension to the conflict. The ATB system destabilizes the turn order, so the results become a lot less predictable. You and your opponent are at low health. Getting off a solid hit could be enough to finish off either one of you. Your opponent is a little slower but their ATB gauge is a bit more full than yours. You’re watching the guages fill and yours is catching up. Can you get your attack off before they do?
  3. It animates play. The ATB system serve as a bridge between turn-based RPGs and action-based RPGs. The dial between the two can be adjusted and can stop at any point. Does the gauge pause when someone is ready to take their turn? Can do perform some actions while your gauge is filling? These choices can be used to alter how “snappy” your decisions have to be and how frequently your tactics will have to change. This dial can be a precise tool to improve (God, strike me down for using this term,) the ludonarrative consonance—or the consonance between story and play—in an otherwise familiar play structure. In FFVII’s cyberpunk setting, the use of a non-pausing ATB system helps make it feel like you’re in a firefight, whether you’re firing off Barrett’s gatling arm of casting firaga as Aerith.

Speed in TTRPG’s

Most TTRPG’s use some form of “initiative,” where a higher speed will allow you to act first in the turn order. Other TTRPGS, while not exactly employing the ATB system itself, have found other ways to express speed variance (and some even take inspiration the ATB system in their design). Let’s look at a couple of them.


Errant by Ava Islam modulates the turn order each round (or “initiative turn” as Errant calls it) by inviting a player to call a coin flip. The result of the coin flip will determine if enemies or allies will go first. Players will then be able to choose whether they act quickly (taking one action but taking priority in the turn order) or slowly (taking two actions, but acting in the back half of the turn.) You cannot double up on your spellcasting or attack rolls in this way, however.

While still orienting itself around quick and lethal encounters, Errant shakes up the turn-based standard by shifting the order each round and placing part of that agency in the hands of the players themselves. Speed and action frequency is not only articulated as a choice for the player to make, but is also in sharp contrast with other systems by making the two inversely related. To be quick is to sacrifice a second action. To be slow means to take another.

Last Breath

Jeremy Gage’s WIP game, Last Breath (formerly Umbral Dive), intentionally emulates the flow of the ATB system using an “Impulse Grid,” a piece of turn-based tech that originates in tabletop wargames and that has been used in other RPGs using the Hero System. The grid accounts for a character’s speed by phasing the number of actions a character can take in a single round. A round in Last Breath is made up of 12 turns. Each character’s total number of actions is spread across this total number of turns, and speedier characters are able to take more actions. With all actions spread more or less evenly across these turns, quick characters will find that they act much more frequently than their slower counterparts.

It might be easiest to imagine this systems as though it were a clock. If character A has a speed of 3, they have three actions spread across the clock. As we divide the clock up into three, we will see that they act at 4:00, 8:00, and 12:00. If character B has a speed of 2, they will act at 6:00 and 12:00 instead. Our turn order, then, will be A>B>A>AB.

The numbers used in the example above are not actually possible in Last Breath (character speed ranges between 4-10), but it illustrates how the system makes for a consistent but dynamic turn order where speed makes a dramatic difference in character efficacy. You can learn more about Last Breath by checking out the Umbral Dive devlogs on the Draw Your Dice podcast.

Another Possibility

On the table in front of you there is a gauge with ten or so segments. Each character has a token starting at one end of the gauge.

In this model, each character has their speed reflected with a single die; its size varies depending on the character speed, with a larger die size for speedier characters. Each turn, all characters simultaneously roll their speed dice and move that number of spaces along the gauge.

When a character’s token reaches the end of the gauge, they act. After their turn, they reset their place on the gauge.

Turn order is variable and dynamic. While characters with a higher speed will generally strike more frequently, the character that strike first is always left up to chance. This also has the added benefit of being quite easy to affect another character’s speed with hastening and slowing effects mid-combat. Simply increase or decrease the die size for the next roll.

That’s just one possibility though, and more balanced approaches probably exist. Maybe a speed score is equal to the number of d6’s rolled instead? I am no mathematician, so I might just have to explore this model in play.

2 thoughts on “The Active-Time Model”

  1. I really liked your approach to an ATB gauge in TTRPGs. It adds a sense of variety and adds tension to an otherwise predictable combat. It also helps players more easily understand and visualize when it is their turn. I think a way to balance it could be to have players roll several of their speed die and average them for a better chance at a higher number. Everyone gets a bad streak of rolls once in a while, and not being able to act for several turns could be frustrating for the player

    • I think that’s a great suggestion. It be expressed like “roll Xd6, where X is your speed rating, and keep highest.” In that case, haste/slow effects could also either increase the number of dice rolled or increase die size, depending on how potent you need the effect to be.


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