Sword Combat Theory

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This is somewhat of out of date now

This is an in-depth description of the sword combat design for Coda. You do not need to know any of this to play Coda. A more general explination of Coda's gameplay can be found in the How to Play Coda section. The purpose of this document is to plan for and support high level play.

3/5/09

I outline the gameflow of a classic fighting game, then use this terminology to describe Coda's system as an extension of this one. Even if you have experience with the concepts, I recommend that you go through the outline so you understand the context in which I'm using them.


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In a classic fighting game, characters have a set of moves whos properties do not change. These properties are balanced against one another in a way which makes the move potent in some situations and worthless in others. The idea is that an excellent player can make use of every move in the optimal situation. These properties often include an attack's delay to hit, delay to recover, inflicted damage, High/Low hit location, guard damage and so on.

Where appropriate, these attributes are measured in frames of animation. My examples come from Guilty Gear, which runs at 60 frames per second.

Startup - Number of frames from button press until Active state Active - Number of frames during which enemys can be hit Recovery - Number of frames required to return to active state

"Light" sword slash: Dmg- 10 Startup- 4 Active- 4 Recovery- 6 "Heavy" sword slash: Dmg- 40 Startup- 11 Active- 2 Recovery- 26

These states follow one another through the progress of the character's attack animation. Once an attack starts, no further input is allowed until the sequence completes in full.

If an enemy is hit during an Active frame (blocked or unblocked), the move becomes "Cancelable" - meaning that a Followup attack move is allowed to start during the Recovery phase. A Followup move is a completely fresh move. The current canceled move and it's timings are forgotten and abandoned.

Which moves are allowed as Followups to other moves are explicitly set by the designers on a per move basis, but follow up moves are always more powerful with longer Startup than the initial move.

If a hit connects and is not blocked during the "Active" frames, an extra phase is added called "HitStop". This is a breif ~10 frame window where both characters are frozen. It gives the hit animation a sense of weight, as well as providing the attacking player a window of time to buffer up the next attack command.

When a character gets hit unblocked during an Active frame, they will enter a "HitStun" phase which will play out in parallel to the attacker's Recovery phase. A character in HitStun is not allowed to execute any commands until the HitStun wears off. The length of the HitStun varies depending on the strength of the attack, but usually remains between 10 - 20 frames.

Warmup for fast/weak moves start at 3 frames and slow/strong moves get up to 25 frames. One can easily secure a combo for several fast moves, but to guarantee a combo with a slow move of 18 frames - the defender must have a minimum 18 frames of stun from the prior attack. This means its important to raise the strength of your attacks as much as possible with every Followup so that you can guarantee the large damage moves before the combo falls apart. However, if you get too big too fast with your attacks, your opponent will not have sufficient HitStun and have a chance to block or counter attack.


Coda will extend this system in several ways. Rather than having a set of predefined moves with attributes in the various categories, Coda will have a single sword slash attack. The Startup, Active, Recovery, HitStun, Momentum properties of the attack will be defined dynamically by the player based on his character's movement speed, angle of his strike, previous position of his sword, position of opponent's sword, current Qi power, and modifier keys.

This relieves the player of having to memorize static combos, and makes more room for more creative sequences based on player habits and tendencies.

Coda will unify HitStun and Recovery phases. When a player gets hit, they enter the same Recovery phase the attacker will but with slightly different timings. For a move to successfully Followup an initial hit and create a combo, it must be stronger/slower than the initial hit, or else it will not be allowed to cancel the initial hit's Recovery phase. When a victim is hit, he will be sent to a slightly longer Recovery phase than the attacker, which allows the attacker to follow up with a move that is guaranteed to be faster than any move the victim can come up with. So long as the attacker is careful to keep his attacks strong enough to Followup his initial hit's Recovery, but fast enough to execute within the victim's inflicted Recovery, the combo can continue.

The ability to "block" an attack as seen in classical fighting games will be removed. From the perspective of a classically designed fighting game, characters will constantly be hitting and comboing one another. The difference is that the victim of a combo is an active participant, and can wrestle control of the combo back into his favor at any time.

Orientation of the Recovery is an important aspect to the combo. Each strike has a rotational value depending on which direction the strike happens in. Followups to strikes which are parallel and opposite to the initial strike yield more powerful but slower results. Aside from simply striking back at his attacker, a victim locked in a combo chain can "Deflect" his opponent's strikes. This means, he will deliberately take a hit from his opponent, with the intention of redirecting the attacker's Recovery time and orientation thereby disrupting the combo he had intended and giving the victim a more solid chance to counter. Imagine this mechanic as less drastic than a Soul Caliber style counter, and closer to a Street Fighter 3 parry. It will more subtly redirect the resulting Recovery of an attacker's strike in a way that will slowly give the victim more headway.

Its important to keep in mind the role that player position and movement will be playing through the course of a Rally. Each strike will have an impact on player character momentum, and will tend to push the players apart from one another. This is something each player has a direct impact on and they will plan ahead to engineer this relationship to their advantage.

Separate from this system, but also important to keep in mind is that Coda does not work on life bars or health percentages. Sword combat energy is one of five different types of energy available to a Coda player. It refills itself quickly over time, but in the course of a combo can be reduced past zero. When this happens, the player is no longer able to attack, and he must wait for one of the other energy types to compensate and recover the sword energy. If a player is attacked in this state, he will die.

The HitStop time will be crucial to Coda's network play.