Game launcher attack systems explained

What a launcher attack is

A launcher is any attack whose primary purpose is to put the defender into an aerial or float hurt state so the attacker can continue with juggle follow-ups. Unlike a move that merely deals high damage, a launcher optimizes for route extension: it trades single-hit payoff for access to air chains, wall routes, and meter spend windows.

Launchers differ from generic knockback in three ways:

• Juggle eligibility — the defender enters a state where subsequent hits apply aerial hitstun and obey juggle limits, not grounded blockstun or knockdown.
• Controlled trajectory — launch angle, initial velocity, and gravity multiplier are authored per move, not inherited from a global knockback table alone.
• Follow-up contracts — the move tags which follow-ups are legal (air specials, air dash extensions, wall bounce, OTG) via an explicit route table.

A heavy punch that sends an opponent sliding across the floor is knockback. The same punch with an upward impulse and juggle_entry=true is a launcher. The animation may look similar; the state machine branch is not.

Launcher taxonomy

Most fighters mix several launcher archetypes. Naming them consistently in design docs prevents engineers from bolting incompatible flags onto the same animation.

Vertical launch

Classic uppercut or rising special: steep upward velocity, short horizontal drift. Used after counter-hit confirms or as a risky anti-air reversal. High reward, long recovery on whiff.

Diagonal launch

Sends the defender toward the corner at 30–60°. Enables corner carry without a separate wall-splat move. Pairs with wall bounce routes when the trajectory intersects stage geometry early.

Sweep float

Low-profile launcher: a sweep or shin kick that pops the defender into a shallow float instead of a knockdown. Strong high/low complement because block-low players eat the float unexpectedly. Float height is usually capped so follow-ups are character-specific.

Bounce and splat entry

Some games use a ground bounce or wall splat as the juggle entry rather than a dedicated “launcher” move. Ground bounce and wall break systems can inherit launcher routing if the FSM exposes a shared juggle_eligible parent state.

Command and meter launchers

Motion-input or meter-spend launchers (e.g. EX shoryu, super uppercut) trade resource for reliability: lower startup, higher float, or armor on the way up. Document whether meter enhances an existing launcher or replaces it with a distinct move ID.

Juggle-entry state machine

Implementation quality lives in the FSM. A minimal launcher stack looks like this:

1. Grounded hit — defender in standing or crouching hurt; launcher hitbox active frames tagged launch_type.
2. Launch impulse — apply velocity vector; set gravity multiplier; optionally freeze attacker briefly for hitstop readability.
3. Juggle eligible — defender flagged airborne_hurt=true; juggle counter increments; decay curves from juggle-limit system attach.
4. Follow-up window — attacker may cancel into air normals, air specials, or air dash per route table until juggle cap or forced knockdown.

Critical edge cases:

• Air-to-air launch — defender already airborne; launcher may reset juggle decay or apply a separate “air launch” tier with shorter float.
• OTG launch — moves that pick up downed opponents need a distinct entry flag so they do not double-count juggle budget; see OTG design.
• Launch immunity — super armor or juggle-resistant states may convert launch impulse into stagger instead; document per-move overrides.

Counter-hit launch bonus and scaling

Many games reward counter-hit launchers with extra float time or one free juggle hit before decay accelerates. Harbor Brawl added a ch_launch_bonus field: counter-hit vertical launchers gained +4 frames of float and +1 juggle point before the decay curve steepened. Ground-only counter-hit routes kept the old bonus (extra frame advantage) so players had a reason to fish CH launchers without making them mandatory.

Pair launchers with combo scaling deliberately. If every launcher opens a 12-hit route, damage inflates unless scaling per hit in the aerial phase is harsher than the ground phase. Harbor Brawl used scaling_group=launcher_open starting at 0.85× on hit 3 of the aerial segment.

Risk, startup, and whiff recovery

Launchers are combo glue because they are expensive on failure. Design axes:

• Startup — slow launchers work as anti-air rewards or frame-trap enders; fast launchers work as poke confirms but should float lower.
• Recovery — landing lag after an aerial launcher whiff is a common punish point; grounded launchers expose upper-body hurtboxes.
• Range — long-range sweep floats extend neutral but need minus-on-block recovery so defense can reset.
• Invincibility — reversal launchers often carry upper-body invuln; tag frames explicitly so rollback netcode replays match.

Telemetry: track launcher_attempts, launcher_hit_rate, and avg_hits_after_launch per move ID. A launcher with 40% hit rate but 9-hit average conversion is healthy; 70% hit rate with 3-hit average suggests float is too weak or follow-ups are missing.

Harbor Brawl refactor (case study)

Before the refactor, six characters shared one generic “launch knockback tier” copied from the platform fighter template. Anti-air jabs popped opponents visually but set knockdown=soft, ending pressure. The team:

1. Audited every move with upward impulse; assigned launch_type (vertical, diagonal, sweep_float, none).
2. Added route tables per character: which air normals and specials connect after each launch type.
3. Split “pop-up” anti-air jab (no juggle) from rising special (full launch) to clarify player expectations.
4. Synced gravity multipliers with jump arc constants so float height matched jump height readability.
5. Regression-tested against combo reset and wall routes so corner carry did not exceed stage width caps.

Results after two weeks of ranked play (internal telemetry, not public leaderboard): average combo length 5.1→8.7 hits; aerial damage share 22→41%; launcher whiff punish rate +6% (expected); one-touch rate unchanged at 4.2%.

Technique decision table

Default for anime or tag fighters: at least two launch entry points per character (one grounded, one anti-air or meter) with shared juggle decay rules. Default for grounded realism fighters: one rare launcher with long recovery and strict scaling.

Common pitfalls

• Visual launch without juggle flag — opponent pops up but enters knockdown; players blame “broken combos.”
• One global float height — sweep floats and uppercuts share physics; sweep routes become infinite or useless.
• Missing air follow-ups — launcher exists but character has no air chains; telemetry shows launch hits with zero conversion.
• Inflated damage via launch — longer routes without scaling groups raise one-touch frequency.
• Launcher on block — unsafe launchers that still apply blockstun confuse; tag block version separately or use airborne recovery.
• Rollback desync — launch impulse order differs client vs server; log launch frame and velocity hash in replay tests.
• Duplicate juggle entry — OTG pickup plus launch on same move double-counts juggle budget.

Production checklist

• Define launch_type enum and document per move in the moveset sheet.
• Separate juggle_entry from generic knockdown flags in the hit script.
• Author velocity, angle, gravity multiplier, and float cap per launcher.
• Build follow-up route tables (move ID → legal cancels after each launch type).
• Wire juggle counter increment and decay on entry state, not on first air hit.
• Apply scaling group for launcher-opened routes in the damage pipeline.
• Tag counter-hit launch bonuses explicitly; test CH vs normal float delta.
• Instrument hit rate, conversion length, and whiff punish rate per launcher.
• Regression-test wall bounce, OTG, and combo reset interactions.
• Verify rollback replays for launch frame on CI with recorded inputs.

Key takeaways

• Launchers are route openers — they trade single-hit damage for juggle-eligible float states with authored trajectories.
• Taxonomy matters: vertical, diagonal, sweep float, and bounce entry need distinct physics and follow-up tables.
• Harbor Brawl raised average combo length 5.1→8.7 hits by fixing juggle-entry flags, not by buffing damage.
• Pair every launcher with scaling groups and juggle decay so longer routes do not inflate one-touch kills.
• Telemetry on conversion length after launch catches “pop-up” animations that fail to enable juggles.

Related reading

• Juggle limit and decay systems explained — caps and decay after launch entry
• Anti-air systems explained — common launcher trigger context
• Knockback systems explained — impulse models launchers build on
• Combo damage scaling systems explained — keep aerial routes fair