Combat system

Combat System

Build the combat core of an action game — melee and ranged — over one unified pipeline, with the RPG/balance math underneath. Primary reference: Granblue Fantasy: Relink (combo chains in the Monster Hunter lineage), with CS/Overwatch (gunplay) and XCOM/Pokémon/WoW (RPG math) as calibration poles. This skill is the engine-agnostic blueprint: the attack graph, hit detection, the damage pipeline, the stagger economy, the defensive kit, ranged/gunplay, turn-based/RPG architecture, feel numbers, and failure modes. Excluded (separate skills): enemy AI (enemy-ai-framework), combat camera (camera-system), stats/equipment progression (progression-economy).

Pick your philosophy first

Every number in a combat system depends on one upstream choice — where you sit on the commitment ↔ freeform dial:

Dial	Commitment (MH / souls)	Freeform (DMC / Bayonetta)	Relink
Cancels	Almost none	Everything → dodge/jump	Middle: dodge keeps string position
Dodge	Long, big i-frames, costly recovery	Short, spammable, perfect-fishing	Spammable + perfect reward
Hit-stop	Attacker-only, heavy	Both, short	Light, both
Defense reward	Survival	Style/Witch Time offense	Stun gauge → Link economy
Input buffer	Short/strict	Generous	Generous

Pick one column as the spine; borrow from the other deliberately, never by default. Mixing (e.g. freeform cancels + commitment damage) produces mush.

The core model: a data-driven attack graph

The combo system is a graph authored as data (this is literally how MH ships its weapon movesets, as FSM files with priority-ordered transition lists):

• Node = attack: {anim, windows (hitbox/cancel/branch), motion value, damage cap, costs/gains, hyperarmor frames}
• Edge = transition: {input, time window, state predicate (on-hit, resource, mode, charge-held)} — edges ordered by priority (composed inputs evaluated before simple ones they contain).
• Branch types: on-input (light/heavy/directional), on-hit vs on-whiff, charge (hold), finishers (string payoff, often feeding a resource — Relink's finishers level up skill power).
• Cancel semantics are explicit per edge: Relink ships both — dodge cancel preserves string position (Bayonetta's Dodge Offset), guard cancel resets it. Preserve / reset / offset is a per-edge data field.

Designers add chains without touching code. The graph plugs into the movement HSM (character-controller skill) as the combat state's content.

Reference map

File	Covers
attack-graph.md	The melee core: the data-driven attack graph (nodes/edges, cancel semantics), animation-driven hit detection (the unified HitEvent, sweep traces, the hit registry), the damage pipeline (motion values, caps), stagger/poise/break, the defensive kit (dodge/guard/parry), the skills/link layer, the feedback layer (hit-stop, screenshake, knockback)
ranged-gunplay.md	The ranged half: gun feel (cumulative micro-feedback), recoil patterns and spread/bloom/ADS, hitscan vs projectile architecture (pooling, sub-stepping), aiming and aim assist, ranged hit-registration and lag-compensation netcode, headshot/falloff/TTK-breakpoint damage, mixing melee + ranged
rpg-combat.md	The RPG/turn-based/balance layer: turn and initiative models (ATB/CTB/tactical grid, the action economy, the Gambit model), the damage-formula design space (additive vs multiplicative, mitigation curves, Effective HP), stats and scaling, status effects and CC diminishing returns, balance via DPS/TTK/EHP, the action-RPG bridge (build-up meters, MH hitzones, MMO GCD, Genshin reactions)
pitfalls.md	14 failure modes (symptom → cause → prevention) with debugging order and playtest checklist

Build order (4 shippable tiers)

Tier 1 — Hitting things
- [ ] Attack graph data format (nodes/edges) + a 3-hit string
- [ ] Animation-driven hitbox windows (tags on the timeline, never timers)
- [ ] Hit registry (one hit per target per swing) + HitEvent pipeline
- [ ] Damage = base x motion value; hit-stop on contact (attacker + victim)
Tier 2 — Responsiveness
- [ ] Input buffer (intent + timestamp, ~150-300 ms, depth 1, newest wins)
- [ ] Cancel windows per type (dodge/guard/skill) with explicit semantics
- [ ] Dodge with authored i-frames; guard with chip + guard-break gauge
- [ ] On-hit vs on-whiff branching; sweep traces for fast swings
Tier 3 — The reward economy
- [ ] Stagger: poise/flinch per attack + accumulated stun gauge -> 
      vulnerability window (Link Time model)
- [ ] Boss state cycle (Normal -> Overdrive -> Break) modulating damage
      taken/dealt and AI gating
- [ ] Perfect dodge / perfect guard (tight window, asymmetric rewards)
- [ ] Skills layer: cooldown slots + ultimate gauge, decoupled from the
      graph (skill = near-universal cancel target)
Tier 4 — Depth & scale
- [ ] Charge attacks, breakable parts (separate HP pools, MH model)
- [ ] Damage caps per node (Relink model) if long-tail gear progression
- [ ] Party/link layer: shared gauges + synchronized vulnerability windows
- [ ] Per-character graph variants over the shared data model

Feel numbers (starting points — tune by playtest)

Parameter	Starting point	Anchor
Hit-stop light / medium / heavy / finisher	2-4f / 4-8f / 8-15f / 15-30f (@60)	Smash formula ⌊dmg×0.65+6⌋ cap 30f; SF6 10-20f
Hit-stop scope	attacker + victim; world-freeze for finishers only	MH freezes attacker only (weapon "bite") — a deliberate exception
Dodge total / i-frames	25-40f total; i-frames first 40-60%	Elden Ring 13f@30 i-frames; MH base 250 ms + skill investment
Perfect guard / parry window	5-8f (83-133 ms)	Sekiro 12f@60 shrinking on spam; Relink ~5f (community)
Perfect dodge window	10-15f — ~2x more lenient than parry, lower reward	Relink consensus; Bayonetta ~20f
Slow-mo reward	2-4 s at 0.1-0.3x enemy speed	Witch Time 0.5-3 s
Attack input buffer	10-18f (167-300 ms), depth 1	FG 4-8f; action games run longer
On-hit cancel opens	at hit + hit-stop end (~20-30% earlier than whiff)	SF6 on-hit-only specials
Combo next-input grace	0.3-0.5 s after recovery-cancel point	MH delay-tolerant strings
Motion values light / heavy / charged	20-50 / 50-80 / 100-180 (% of base)	MH GS charge lv3 = 100-120
Crit	x1.25, build-up to x1.5	MH affinity model
Stun gauge threshold	~8-15 light hits; +50-100% per proc (anti-stunlock)	MH KO escalation
Break/KO window	8-15 s; damage taken x1.2-1.5	Relink Break, MH KO
Screen shake	0.15-0.25 s, trauma² amplitude, Perlin not random	GDC Juicing Your Cameras

Full sourced tables in attack-graph.md; ranged TTK/ falloff in ranged-gunplay.md; damage-formula and balance math in rpg-combat.md.

Engine mapping

Generic block	Unity 6	UE5 (5.4+)
Attack graph data	ScriptableObject attack assets referencing next-node assets	GameplayAbilities + montage sections (single combo ability) or ability-per-attack chained by tags; GameplayTags as cancel rules
Hitbox windows	Animation events (prefer Animancer/Playables delegates over string events) toggling Physics.OverlapCapsuleNonAlloc per frame — not trigger colliders	AnimNotifyState (HitWindow/ComboWindow/InterruptWindow) doing per-tick socket sweep traces
Fast-swing safety	CapsuleCast from last-frame to current socket position	path-trace previous→current socket per tick
Damage pipeline	IDamageable + DamageInfo struct + C# events for feedback	GameplayEffect + ExecutionCalculation + meta attribute; GameplayCues for feedback
Hit-stop	per-Animator.speed on attacker+victim (NOT global Time.timeScale)	CustomTimeDilation per actor (NOT global dilation); cosmetic-only in netplay
Attack lunge/tracking	clamp steering in OnAnimatorMove	Motion Warping with translation/rotation limits
GAS-like layer	community GAS ports (no first-party); attributes+tags+effects+cues pattern	GAS is the standard backbone

Failure modes

The 14 classic combat bugs (hitbox desync, multi-hit duplicates, point-blank whiffs, eaten inputs, animation pops on cancel, hit-stop bleeding into UI/co-op, stagger-lock, duplicate damage, cancel exploits, knockback through walls, tracking overshoot, graph/state desync, ranged hit-reg "I shot them but no hit", and runaway or stagnant damage numbers) are cataloged in pitfalls.md with symptom → root cause → prevention.