Momentum¶

The Commitment Curve¶

A real sword swing has a momentum profile. The weapon has mass. Muscles apply force. Momentum builds. At some point, the momentum exceeds what the wielder's strength can redirect — the swing is committed. Before that point, the wielder can change their mind.

Initiation ──→ Acceleration ──→ Committed ──→ Contact/Whiff ──→ Recovery
   │                │                │              │               │
   Full redirect    Partial          Physics        Vulnerable
   (any direction)  redirect         takes over     (momentum
   Low cost         (costs force)    No cancel      must decay)
   │                │                │              │
   └── FEINT WINDOW ┘                └── COMMITTED ─┘

None of these are frame counts. They are physics states. The transition from "feintable" to "committed" is when weaponMomentum > redirectThreshold × characterStrength. A dagger with 0.3kg reaches commitment later than a greatsword with 3kg because it takes longer to build irrecoverable momentum. The threshold is physics — mass, force, angular velocity — not an arbitrary cancel window.

The commitment curve is continuous. There is no binary "can cancel / can't cancel" state. The cost of redirecting increases smoothly with momentum. A redirect at 20% momentum is nearly free. A redirect at 80% momentum is a visible, time-consuming arc that the opponent can read and punish. The player decides moment-to-moment how much momentum to invest before committing.

Feints¶

A feint is: begin applying force in direction A, let the opponent read direction A and start reacting, then redirect to direction B before commitment.

How Feints Work¶

1. Player inputs attack direction A (footwork-relative)
2. Character's muscles apply torque, weapon begins rotating toward A
3. Weapon's angular velocity builds, visible to the opponent
4. Player inputs direction B while momentum < redirectThreshold
5. Muscle force redirects — the weapon curves, decelerating in A's direction and accelerating in B's direction
6. The redirect is not instant — it takes time proportional to how much A-momentum was built
7. The opponent who committed to defending A is now open to B

Why Physics Feints Are Deeper Than Animation Feints¶

In traditional games, a feint is "play first 5 frames of attack A, then play attack B." The opponent learns the animation tell. The counterplay is pattern recognition — memorize what the first 5 frames look like, then react.

In a physics system, the feint's timing is continuous. The player can redirect at any point in the initiation window, with different costs and trajectories:

• Early feint (10-20% momentum). Almost invisible. The weapon barely moved before changing direction. Hard to read as a feint. Hard to sell as a real attack. Low commitment, low reward.
• Mid feint (40-60% momentum). Visible wind-up that forces a defensive reaction. The redirect costs noticeable time — the weapon traces a curved arc from A to B. The curve itself reveals that a feint occurred, but the defender has already committed.
• Late feint (70-85% momentum). A dramatic redirect that looks like a failed attack redirected through sheer force. The weapon takes a wide arc from A to B. Maximum sell — the defender was certain the attack was committed. Maximum cost — the redirect time is long enough that a fast opponent can recover and counter.

The opponent must read the momentum, not the animation. There is no "feint animation" to memorize. There is a weapon moving through space with accelerating momentum, and the defender must judge whether the attacker has passed the commitment threshold or is still in the feint window.

Feint Quality by Weapon¶

The dagger user feints constantly because they can, but each feint is subtle. The greatsword user feints rarely because the window is short, but each feint is devastating when it lands. The sword user plays the middle. None of this is designed as balance — it emerges from F = ma applied to different mass distributions.

Cancels¶

"Cancel" in a physics system means arresting momentum. There is no "cancel button." There are three physical methods of stopping a committed action, each with different costs and consequences.

Pull Back (Soft Cancel)¶

Reverse the muscle force. The weapon decelerates, stops, returns to guard.

Cost: Time. The heavier the weapon and the more momentum built, the longer the deceleration takes. During deceleration, the weapon is neither attacking nor defending — it occupies dead space. The player is vulnerable for the duration of the deceleration.

Weapon scaling: A dagger pulls back in frames. A greatsword pulls back in a visible, punishable arc that takes real time. The pull-back IS the recovery — not a fixed frame count, but the physics of decelerating a mass that was accelerating.

Redirect Into Guard (Hard Cancel)¶

Instead of killing the momentum, redirect it into a defensive position. The swing curves into a parry stance.

Cost: Faster than pull-back because the momentum is used instead of fought. But the resulting guard position is constrained by where the momentum takes the weapon. The player does not choose which guard — the physics chooses based on the swing direction and the redirect timing.

A horizontal sweep redirected into guard produces a lateral guard position. A vertical overhead redirected into guard produces a high guard. The guard you get is the guard the physics produces. This creates emergent defensive positions that depend on what attack the player was attempting when they cancelled.

Depth: The skilled player knows which guard each redirect produces and incorporates that into their planning. "If I start a sweep and redirect, I get a lateral guard — which covers the opponent's likely counter-angle." The cancel becomes part of the defensive toolkit, not an escape from commitment.

Release Into Movement (Dodge Cancel)¶

Stop controlling the weapon and move the body. The weapon trails behind, carried by its own momentum.

Cost: Fastest escape option — the body dodges while the sword is still swinging through empty space. But the weapon is uncontrolled during the dodge. No parry, no attack, no guard until the weapon settles into a neutral position after its momentum decays. The recovery is the weapon's physics, not a frame count.

Risk: An opponent who reads the dodge cancel can time their attack to arrive during the weapon-recovery window — after the dodge but before the weapon is controllable. The dodge cancel trades immediate safety for extended vulnerability.

The Read¶

Combat between skilled opponents is a conversation about momentum. The attacker invests momentum. The defender reads the investment and decides: is this committed or feintable?

What the Opponent Reads¶

1. Feet first. Weight shift reveals intent before the weapon moves. A feint that sells the feet sells the read. A player who moves forward (generating a thrust) but redirects the weapon laterally (sweep) has sold the footwork but not the blade — a skilled opponent reads the feet and ignores the blade.

2. Weapon acceleration. How fast is momentum building? A committed attack accelerates aggressively — the attacker is investing maximum muscle force because they intend to follow through. A feint accelerates cautiously — the attacker is hedging, keeping the option to redirect. The acceleration curve is the tell.

3. Shoulder and hip rotation. The body's kinematic chain transfers force from feet through hips through shoulders to the weapon. Deep rotation means deep commitment — the entire body is behind the swing. Shallow rotation means the attacker is preserving the option to redirect. An experienced defender reads the rotation angle, not the weapon position.

4. The redirect moment. When the weapon curves, the curvature is visible. A late redirect (high momentum) creates a wide arc the defender can read and punish. An early redirect (low momentum) is subtle but less threatening. The redirect itself becomes information — the opponent knows a feint occurred and adjusts.

AI Reading¶

AI opponents read the same physics values: angular velocity, acceleration derivative (jerk), body rotation angle, foot pressure distribution. A skilled AI opponent reads the commitment curve the same way a HEMA practitioner reads their opponent — by watching the physics of the body, not by pattern-matching animation frames.

The AI's reading accuracy scales with the enemy's skill level:

• Fodder enemies react to the weapon position (slow, easily feinted)
• Competent enemies react to the weapon velocity (moderate, can be feinted with late redirects)
• Skilled enemies react to the body rotation (hard to feint — they see commitment before the weapon reveals it)
• Boss enemies react to the feet (nearly impossible to feint — they read intent at the source)

Michael at the Throne reads the feet. He designed the footwork every being in the game uses. The architect reads the architecture.

The Bind as Cancel State¶

The bind — sustained weapon contact — is the deepest expression of the momentum system. Two locked weapons, both with momentum, both fighters choosing micro-redirects in real time.

Every bind transition is a momentum decision:

• Wind is a redirect within contact — the weapon slides along the opponent's blade toward their body. The momentum curves around the contact point.
• Displace is a force commitment — pushing the opponent's weapon aside requires investing more momentum into the bind than they are. Superior leverage or angle wins.
• Withdraw is a pull-back cancel from contact — creating distance but surrendering initiative. The opponent's momentum is no longer opposed and they can follow through.
• Pommel strike is a partial cancel — one hand releases the main grip, the other drives the pommel forward. Only viable in very close bind where the pommel reaches the opponent's body.
• Grapple transition is a release into movement — the weapon is abandoned as the primary tool and the fighter closes to body contact. The entry to absorption range.

The bind IS the cancel system at its deepest expression. Both fighters are simultaneously committed (weapons locked) and choosing (micro-redirects within the contact). The commitment curve is not a precursor to combat — it is present within every moment of sustained contact.

Weapon-Specific Momentum¶

The commitment curve makes each weapon feel mechanically distinct without stat sheets:

The dagger user feints constantly because they can. The greatsword user commits because they must. The sword user plays the middle. The fist user never commits to a strike — every motion is a potential feint, a potential strike, a potential grab. The transition from punch to absorption is the most ambiguous moment in the combat system — was that a feint, a strike, or the beginning of the most destructive power in the game?

Momentum and Absorption¶

The momentum system connects directly to the game's core mechanic. Absorption requires grapple range — body contact. Getting to grapple range requires closing through the opponent's weapon's effective range. The commitment curve determines how the player closes that gap.

Aggressive close: The player commits forward momentum, tanking or evading strikes to reach grapple range. The momentum of the approach becomes the momentum of the absorption. The consent tracker records the aggression.

Patient close: The player reads the opponent's commitment curve, waits for a committed swing, uses the recovery window to close. The absorption follows a moment of the opponent's vulnerability. The consent tracker records the patience.

Feint close: The player feints a weapon attack, the opponent commits to defense, and the player redirects from weapon momentum into forward movement — closing past the guard before the opponent can react. The feint becomes the approach. The consent tracker records the deception.

Bind close: From the bind, the player transitions to grapple. The weapons are locked, the distance is already close, the redirect is into body contact. The most intimate transition — from mutual commitment to absorption. The consent tracker records the path through the bind.

Each closure path tells a different story about how God reached the being. The momentum system generates the story. The consent tracker preserves it. The endings read it.

Relationship to the Design Philosophy¶

The momentum system passes the fusion test:

• Character: The player's feint frequency, commitment depth, and cancel patterns reveal their approach to combat. The aggressive closer who never feints. The patient reader who feints constantly. The greatsword user who commits fully every time. The dagger user who never commits until the moment of absorption. The footwork IS the character. The momentum IS the character.
• Theme: The commitment curve mirrors the game's central question — how much do you invest before you can't take it back? Every swing is a micro-version of the pilgrimage's arcs. Commit to the water or sail over. Commit to the truth or maintain the fiction. Commit to the swing or redirect. The cost of commitment scales with investment, in combat and in the story.
• Gameplay: The momentum is the gameplay. Distance, angle, mass, force, timing — all real, all interactive, all skill-testing. The feint window is skill expression. The commitment read is spatial intelligence. The bind transitions are deep mechanical knowledge. No abstraction between the player's decision and the physical result.

The combat is a conversation spoken in Newtons. The momentum system is the grammar.