Game feel (juice)
The difference between a mechanic that works and one that feels good is feedback: the
layered, slightly-exaggerated response an action provokes. This skill covers the engine-
neutral techniques — screen shake, hit-stop, easing, squash & stretch, knockback, and stacked
feedback — and tells you how to apply them without burying the underlying simulation. It
adds polish on top of an existing mechanic; it does not implement the mechanic.
When to use
- Use when an action (hit, jump, dash, pickup, death, button press) is mechanically correct
but feels weak, weightless, or unsatisfying, and you want it to feel responsive and punchy.
- Use to add screen shake, hit-stop/freeze frames, eased motion, squash & stretch, knockback,
flashes, or to layer multiple feedback channels onto one event.
- Use to decide how much juice is enough and where it crosses into noise.
When not to use: for the raw controller math (jump height, coyote time) use the
platformer genre and the engine movement skill. For camera follow/deadzone/orbit framing
use camera-systems (this skill only triggers the shake). For mixing, ducking, and adaptive
music use audio-design. For shader-based dissolves/flashes use shader-programming and the
engine shader skill. For the concrete tween/particle node APIs, use the engine animation skill
(godot-animation, unity-animation).
Core principle: feedback is layered and exaggerated
One satisfying hit is usually 5–8 tiny responses firing together within ~100 ms: a sound,
a particle burst, a brief hit-stop, a flash, a knockback, a small screen shake, and a number
popping up. Each is cheap; stacked, they read as "impact". Two rules keep it from becoming a
mess: (1) exaggerate briefly and return to rest (juice is transient, not a new resting
state); (2) scale juice to event importance — a footstep is not a boss death.
Core workflow
- Confirm the event hooks exist. Juice attaches to discrete events:
on_hit, on_land,
on_pickup, on_death, on_fire. If the mechanic doesn't emit these, add them first.
- Pick feedback channels per event from the menu (sound, particles, shake, hit-stop,
flash, knockback, tween, number pop). Start with 2–3; add until it reads, then stop.
- Make motion eased, not linear. Route scale/position/UI changes through a tween with an
ease (overshoot for "pop", ease-out for "settle"). Linear motion feels robotic.
- Reserve hit-stop and shake for impact. They are the strongest, most abusable tools —
short durations, scaled to importance, and never on routine actions.
- Keep feedback off the critical simulation. Shake moves the camera/visual, not the
body; hit-stop uses time scale or a real-time pause, not a gameplay-logic stall.
- Tune by importance tiers. Define small/medium/large feedback presets and assign events
to a tier, so the whole game's juice stays consistent and proportional.
- Verify by playing and watching. Trigger the event repeatedly; confirm the feedback
fires, returns to rest, and is not nauseating or input-blocking. Report what you observed
(does shake decay? does input still register during hit-stop?).
Patterns
1. Screen shake by decaying "trauma" (smooth, not a random jitter)
## Godot 4.7. Store trauma 0..1; shake = trauma^2 so small hits barely move, big hits punch.
## Drives a Camera2D OFFSET (the visual), never the player body. Decays every frame.
@export var decay := 1.2 # trauma lost per second
@export var max_offset := Vector2(12, 8)
@export var max_roll := 0.1 # radians
var trauma := 0.0
var _t := 0.0
func add_trauma(amount: float) -> void:
trauma = clampf(trauma + amount, 0.0, 1.0) # hits ADD; they don't reset
func _process(dt: float) -> void:
if trauma <= 0.0: return
trauma = maxf(trauma - decay * dt, 0.0)
var shake := trauma * trauma # quadratic: gentle low, sharp high
_t += dt * 30.0
# Smooth pseudo-random via sampled noise/sin, NOT rand each frame (that buzzes).
offset = Vector2(max_offset.x * shake * sin(_t * 1.7),
max_offset.y * shake * sin(_t * 2.3))
rotation = max_roll * shake * sin(_t * 1.1)
## Unity 6.3 LTS: identical model on a CinemachineCamera via CinemachineBasicMultiChannelPerlin
## (set AmplitudeGain/FrequencyGain from trauma^2) — see camera-systems.
2. Hit-stop / freeze frame (sell impact by briefly stopping time)
## Godot 4.7. Drop time scale, then restore after a REAL-TIME delay (unaffected by time_scale).
func hit_stop(duration := 0.08, scale := 0.05) -> void:
Engine.time_scale = scale
# 4th arg ignore_time_scale=true → the timer still fires while the game is frozen.
await get_tree().create_timer(duration, true, false, true).timeout
Engine.time_scale = 1.0
// Unity 6.3 LTS (C#). WaitForSecondsRealtime ignores Time.timeScale, so the timer still elapses.
IEnumerator HitStop(float duration = 0.08f, float scale = 0.05f) {
Time.timeScale = scale;
yield return new WaitForSecondsRealtime(duration);
Time.timeScale = 1f; // RIGHT: real-time wait. WRONG: WaitForSeconds (never resumes at scale 0)
}
3. Squash & stretch + overshoot via an eased tween (the "pop")
## Godot 4.7. Conserve volume: stretch one axis, squash the other, then spring back with overshoot.
func pop(node: Node2D) -> void:
node.scale = Vector2(1.3, 0.7) # instant squash on the event
var tw := create_tween()
tw.tween_property(node, "scale", Vector2.ONE, 0.18) \
.set_trans(Tween.TRANS_BACK).set_ease(Tween.EASE_OUT) # BACK = overshoots past 1, settles
## RIGHT: ease back (TRANS_BACK/ELASTIC) for life. WRONG: linear tween → mechanical, dead.
4. A feedback bundle scaled by importance (keep juice proportional)
## One call per event; the tier decides intensity so the whole game stays consistent.
func feedback(event_pos: Vector2, tier: String) -> void:
match tier:
"small": AudioBus.play("tick"); Camera.add_trauma(0.15)
"medium": AudioBus.play("hit"); Camera.add_trauma(0.4); hit_stop(0.05); spawn_particles(event_pos, 6)
"large": AudioBus.play("boom"); Camera.add_trauma(0.8); hit_stop(0.12); spawn_particles(event_pos, 30); flash_white(0.06)
Pitfalls
- Shaking the player/body instead of the camera offset desyncs collision and aim. Shake
the camera (or a visual pivot), never the simulated transform.
- Random offset every frame buzzes like static. Drive shake from sampled noise/sin and a
decaying trauma value so it's smooth and self-ending.
- Hit-stop with
WaitForSeconds / a scaled timer never resumes (at time scale 0 the timer
never advances). Use a real-time wait (WaitForSecondsRealtime, or Godot's
ignore_time_scale timer).
- Hit-stop on every frame of a held attack locks the game. Trigger it once per impact.
- Linear tweens everywhere feel robotic. Ease almost everything; reserve overshoot
(BACK/ELASTIC) for "pop" and ease-out for "settle".
- Permanent exaggeration (scale never returns, shake never decays) becomes the new normal
and stops reading as feedback. Juice must return to rest.
- Over-juicing routine actions (full shake + hit-stop on every footstep) causes nausea and
hides real impacts. Scale to importance; add a "reduce screen shake"/"reduce flashing"
accessibility option.
- Feedback that blocks input (long freeze, un-cancelable animation) hurts responsiveness.
Keep juice short and let input buffer through it.
References
- For the trauma-shake math, easing-curve cheat sheet (which ease for pop vs settle), knockback
- flash + number-pop recipes, importance-tier presets, and per-engine tween/particle bindings,
read
references/feedback-recipes.md.
Related skills
camera-systems — owns camera follow/deadzone/orbit; this skill only feeds it shake trauma.godot-animation, unity-animation — concrete tween/AnimationPlayer/particle APIs juice rides on.audio-design — the sound layer of every feedback bundle; ducking and SFX variation.physics-tuning — knockback forces and the timestep juice must not destabilize.platformer, fps-shooter, roguelike — genres whose moment-to-moment feel this elevates.