Guide

Game juggle and launch combo systems explained

Harbor Siege's act-one brawler loop felt flat: every enemy reacted to hits with the same ground stagger and a two-second knockdown. Players mastered one optimal string and repeated it for twenty levels. After refactoring the combat layer around explicit launch tiers, air hitstun decay, and juggle point budgets, average combo length rose from 4.2 to 9.8 hits and session time in the training yard tripled — without raising per-hit damage. A juggle system is the ruleset that decides when an enemy leaves the ground, how long they stay vulnerable in the air, when gravity reasserts control, and what resets the sequence. It sits downstream of knockback impulse and upstream of combo routing: knockback moves the body; juggle rules govern whether that displacement becomes an extended aerial punish window. This guide covers launch and juggle taxonomy, the hit-resolution pipeline, hitstun and gravity scaling, bounce and OTG (off-the-ground) extensions, enemy tech escapes, damage scaling policies, the Harbor Siege aerial refactor, a technique decision table vs flat knockback-only combat, pitfalls, and a production checklist.

Juggle mode taxonomy

Not every game that launches enemies uses the same juggle philosophy. Pick a primary mode and document exceptions per enemy class.

Mode	Core rule	Genre examples	Player skill ceiling
Finite juggle budget	Each launch grants N air hits or P juggle points; then forced knockdown	Beat-em-ups, action RPGs, musou	Route selection within budget
Decay juggle	Hitstun and launch velocity shrink per successive air hit	Fighting games, arena brawlers	Timing tightness, reset knowledge
Height-gated juggle	Only certain launchers work above/below altitude thresholds	Platform fighters, aerial combat	Spatial awareness, ledge routes
Bounce extension	Wall/floor/corner bounces refresh partial budget or reset decay	Fighters, combo-heavy action	Corner carry, geometry reads
OTG extension	Knockdown state still juggleable with specific moves	Fighters, stylish action	OTG move knowledge, setup routes
Team juggle / relaunch	Allies or assists reset air state mid-combo	Co-op brawlers, tag fighters	Coordination, assist timing

Harbor Siege adopted a hybrid: finite budget per enemy weight class, with decay on hitstun after the third air hit and wall bounces that refund one juggle point if the enemy strikes geometry above mid-screen height.

Launch tier pipeline

A launch is not just “big knockback upward.” Treat launches as enumerated tiers with consistent downstream behavior.

Typical launch tiers

Soft launch — low apex, short float; opens one or two air links. Good for fast characters and pokes.
Standard launch — mid apex, full air combo route. Bread-and-butter launcher from light or heavy ender.
Spike / slam — downward or fast-fall state; OTG follow-up rather than air chain.
Pop-up / float — near-hover at apex; extends juggling for slow, readable aerials.
Horizontal blowback — launches at shallow angle toward wall bounce routes.

Hit resolution order

Armor check — does the hit beat super or hyper armor?
State gate — is the target in a juggleable state (airborne, OTG-eligible, bounce recovery)?
Launch tier assignment — apply vertical velocity, gravity scale override, and rotation lock.
Hitstun application — air hitstun frames, scaled by decay curve and weight class.
Budget debit — subtract juggle points or increment decay counter.
Damage scaling — apply combo damage multiplier for this juggle segment.

Centralize this in a JuggleController component rather than scattering per-attack magic numbers. Harbor Siege moved 47 launcher scripts to a shared resolver; tuning one decay curve updated every character consistently.

Hitstun, gravity, and decay curves

The feel of juggling lives in how long the victim hangs versus how fast they fall. Frame data for air moves must be authored against these curves, not in isolation.

Parameter	What it controls	Tuning lever
Air hitstun	Frames victim cannot act after each air hit	Base frames minus decay per hit (e.g. -3f per link)
Gravity scale	Fall speed while juggleable	Lower gravity = longer combos; raise per hit to force landing
Launch velocity cap	Maximum upward speed per tier	Prevents infinite height from repeated launchers
Float time at apex	Hang frames before gravity dominates	Separate from hitstun; sells impact without extra damage
Weight class multiplier	Heavy enemies juggle shorter	Light 1.0x, medium 0.75x, heavy 0.5x hitstun budget

Plot your decay visually: hit number on the x-axis, remaining hitstun on the y-axis. If the curve crosses below your fastest air move's startup before the budget expires, players hit a “dead zone” where combos fail unpredictably. Harbor added a minimum hitstun floor of 8 frames so advanced routes fail from budget exhaustion, not from math holes.

Bounces, OTG, and relaunch rules

Wall and floor bounces

Bounces convert horizontal displacement into extra juggle time. Define:

Bounce eligibility — only while juggle budget remains; or always once per combo.
Velocity reflection — dampen horizontal speed (0.6–0.8x) to prevent pinball chaos.
Bounce hitstun bonus — +N frames on wall connect so follow-up links remain possible.
Corner carry limit — cap bounces per combo to stop infinite wall loops.

OTG (off-the-ground) attacks

OTG moves strike knocked-down enemies. They extend combos after a juggle ends but usually at reduced damage and with distinct hitstun. Mark OTG-eligible moves in data; do not let every low attack OTG by accident or grounded neutral becomes unsafe.

Relaunch and reset

A relaunch returns a falling enemy to air juggle state. Restrict relaunch moves to EX meter, long recovery, or once-per-combo to avoid infinite loops. A hard reset (knockdown, tech roll, or juggle immunity buff) clears budget and decay counters — enemies need this between player combo attempts in PvE.

Enemy tech escapes and player counterplay

One-sided juggles bore spectators and frustrate players in PvP. Give defenders outs with readable telegraphs.

Air tech — directional recovery at juggle end; invulnerable frames on startup.
Juggle break burst — spend meter to explode out after N hits; boss-only or PvP-only.
Rotation during hitstun — slight facing change on last hit enables escape roll on landing.
Super armor mid-juggle — elite enemies activate armor after budget threshold.

In PvE, tech escapes should be rare on trash mobs and common on mini-bosses. Harbor Siege gives grunts no air tech; captains tech once per fight if the player repeats the same launcher opener three times — nudging route variety without hard counters.

Damage scaling inside juggles

Long juggles inflate DPS unless damage per hit drops. Common policies:

Policy	Formula sketch	Feel
Linear decay	damage × max(0.2, 1 - 0.08 × hitIndex)	Predictable; rewards long routes modestly
Plateau then cliff	Full damage hits 1–5; 50% after; OTG at 25%	Flashy early, safe total DPS cap
Style over damage	Flat damage; juggle builds style meter for finishers	Bayonetta-style; DPS capped by finisher gate

Show scaling in the training UI. If players cannot see why hit 12 deals 40 damage, they blame broken combos instead of intentional caps.

Harbor Siege aerial refactor (worked example)

Before refactor: one launchForce float on heavy attacks; no shared budget. After:

Three launch tiers (soft, standard, blowback) on data-driven move tags.
Juggle budget by weight: light 12 pts, medium 8, heavy 4; each air hit costs 1–3 by move class.
Hitstun decay −4 frames per air hit after the second link.
Wall bounce refunds 1 point if impact occurs above 60% screen height.
OTG sweep on heavy ender only; 30% damage, no budget refund.
Training dummy overlay showing budget, decay, and scaled damage per hit.

Results: combo variety index (unique routes per session) +62%; boss time-to-kill unchanged because damage scaling capped total output. Players reported higher satisfaction despite similar kill speed — expression mattered more than raw DPS.

Technique decision table: juggle system vs alternatives

Design goal	Try first	Add full juggle layer when	Wrong move
Grounded tactical combat	Poise, stagger, position	Genre expects aerial expression (brawler, stylish action)	Launch every enemy on every hit
Short readable encounters	2–3 hit stagger chains	Enemies have enough HP for 8+ hit routes	Infinite juggle on fodder without scaling
PvP fairness	Strict decay + air tech	Competitive mode with balanced roster	Copy PvE budget rules into ranked
Boss spectacle	Phase-specific juggle windows	Boss HP bars justify multi-segment aerials	Permanent boss juggle immunity (wastes player tools)
Low animation budget	Single launch + one air hit	More aerial clips authored	10-hit juggle with repeated hit react

Common pitfalls

Launch without air moves — enemies float with nothing to follow up; always pair tiers with air kit coverage.
Per-script launch forces — inconsistent apex height breaks combo routes; centralize tiers.
No decay or budget — infinite juggles trivialize PvE and break PvP.
Gravity too low globally — victims drift off-screen; clamp position or raise gravity after apex.
Wall pinball — undamped bounces launch enemies into out-of-bounds; add corner damage cap.
Hidden scaling — players do not understand damage drop-off; surface in UI or hit sparks.
Armor ignores not documented — hyper-armor enemies feel broken when launches fail silently.
Multiplayer desync — juggle state must replicate budget and velocity authoritatively.

Production checklist

Define launch tiers and map every launcher move to a tier in data.
Implement shared juggle resolver (budget, decay, scaling) not per-attack logic.
Author air moves with frame data tested against decay curve at hit 1, 5, and 10.
Set weight-class budgets and verify heavies cannot be infinite-juggled.
Configure wall/floor bounce damping and per-combo bounce caps.
Mark OTG moves explicitly; cap OTG damage separately.
Add enemy tech or armor breakouts for elites and PvP defenders.
Plot total DPS cap across max-length juggle; match encounter HP targets.
Build training mode overlay: budget, decay, scaled damage, bounce events.
Regression-test multiplayer juggle state replication under 150 ms RTT.

Key takeaways

Juggle systems are rules on top of knockback: they decide how long aerial punish windows last.
Finite budgets plus hitstun decay prevent infinite loops while keeping routes learnable.
Centralize launch tiers and resolver logic so tuning one curve updates the whole roster.
Harbor Siege gained variety without faster kills by capping DPS scaling inside long juggles.
Bounces, OTG, and tech escapes add depth only when telegraphed and data-tagged.