The canned flinch
A hit plays an animation. Fifty enemies, the same three hit reacts. Players stop seeing them after the first room.
Balance / Injury / Protective reactions
Physics that reacts.
Studios spend years building systems like this in-house. You get it as one drop-in component.
Get it on Fab from $79.99Active ragdoll hit reactions / Unreal Engine 5
Hit them like you mean it.
First hit / Moderate
It staggers.
The hit twists the body. Balance is judged against the feet on the ground, every frame.
Balance under fire
It steps before it falls.
A catch step is committed within a frame of the hit.
Second hit
Hits add up.
The next one lands on a body already fighting for balance, so it counts for more.
Major / Collapse
It goes down fighting.
A full ragdoll with real momentum, not a canned fall.
Physics that reacts
They don't just drop.
They flinch, stagger, fight for balance, step to catch themselves, put their hands out when they fall, carry their wounds, and get back up.
- EngineUE 5.4 · 5.5 · 5.7 · 5.8
- PlatformWindows (Win64)
- DeliveryC++ plugin, source included
- InstallOne component, no engine changes
Motion taken from a real capture of the plugin and re-rendered with AI. Raw Footage is further down the page.
The problem
Your characters have been faking it.
The boneless collapse
Or the character goes limp like someone cut the strings. No effort to stay up, no hands out, no weight.
A body that reacts
Every reaction is physically driven, so no two are alike. Euphoria-style behaviour, sold as one drop-in actor component built on Chaos and Physics Control.
One continuous take
Three hits. One body.
Scroll to fire. Each hit gets a severity, and the severity picks the response.
Motion taken from a real capture of the plugin and re-rendered with AI. Hit order and tiers are from the plugin's own telemetry. Raw footage is further down.
- First hit, upper back, moderate: a stagger. Balance engages and catch steps go out within a frame of the hit.
- Second hit, right shoulder, moderate: a bigger stagger, because repeated hits add up. More catch steps keep it on its feet.
- Third hit, chest, major: collapse. A full ragdoll with momentum transfer, then it settles.
What's in the component
Stagger. Bigger stagger. Collapse.
Five systems do the heavy lifting. Each is described twice: what the player sees, and how it works.
The hit matches the hurt.
- What the player sees
- Small hits flinch, medium hits stagger, big or lethal hits drop the character.
- How it works
- Each hit gets a severity (a velocity change). Thresholds pick Minor, Moderate or Major. Leg and pelvis hits count more, arm hits less, and repeated hits add up.
- MinorPhysical flinch over your animation. Keeps moving, keeps fighting.
- ModerateA real stagger. Balance kicks in and the feet scramble.
- MajorFull ragdoll with momentum transfer.
It steps before it falls.
- What the player sees
- Shoved characters fight to stay up, and throw a foot out to save themselves.
- How it works
- Capture-point balance on the linear inverted pendulum, the same model used in walking robots, judged against the feet on the ground every frame. If the balance can be saved, a procedural step goes out: the right foot, on an arc, at stance width, onto the floor that's actually there.
< 1 frame from hit to committed catch step, before the body has really moved.
It catches itself.
- What the player sees
- Falling characters put their hands out, land on them and brace.
- How it works
- The system predicts the landing spot, reaches out ahead of the shoulders, plants the hands, lets the arms take the weight, then relaxes them.
96 cm/s head speed at the floor with protective arms, against 309 cm/s without.
It holds the wound.
- What the player sees
- Shot arms hang dead and swing. Shot legs limp and buckle. A free hand clutches the wound.
- How it works
- Per-limb injury state that heals over time, with a procedural limp that works with any Anim Blueprint.
- ArmGoes dead, hanging and swinging as they move.
- LegLimps, and gives out under pressure.
- Free handGoes to the injury and holds it.
A hip hit moves the whole person.
- Impulse spread
- A direct share at the impact point, mass-weighted spread through the Physics Asset, and angular transfer that makes hits twist the body.
- Get-up
- Settle detection, face-up or face-down detection, then a get-up montage lined up with the body on the ground. They climb back to their feet without popping.
- Airborne
- Limb motors firm up in the air, so thrown bodies tuck instead of flailing and hands come out near the ground.
Full feature list15 systems, checked against the code
| Feature | What the player sees | How it works |
|---|---|---|
| Tiered response | Small hits flinch, medium hits stagger, big or lethal hits drop the character | Severity per hit (a velocity change); thresholds pick Minor / Moderate / Major. Body-part weighting, cumulative hits |
| Balance | Shoved characters fight to stay up | Capture-point balance (linear inverted pendulum) against the support feet, every frame |
| Catch steps | They throw a foot out to save themselves | Procedural steps: correct foot, on an arc, at stance width, traced onto the floor |
| Protective arms | Hands out, land on them, brace | Landing prediction, reach ahead of the shoulders, plant, bear weight, relax |
| Injuries | Dead arms, limping legs, a hand on the wound | Per-limb injury state, healing over time, procedural limp for any Anim Blueprint |
| Impulse spread | A hip hit moves the whole person; hits twist the body | Direct share at impact, mass-weighted spread through the Physics Asset, angular transfer |
| Get-up | They climb back to their feet without popping | Settle detection, face-up / face-down detection, aligned get-up montage |
| Airborne | Thrown bodies tuck; hands come out near the ground | Limb motors firm up in the air |
| Self-collision | Arms and legs don't pass through each other | CCD on the limbs; missing pairs added to a runtime copy of the Physics Asset |
| Limb control & grabbing | Hands reach targets, pick up and carry objects, grip ledges and bars, hang | Physics-driven limb targets, grip strength, overstretch release, replicated |
| Vehicles & launches | Run-overs; passengers thrown through a windscreen | Kinetic impacts from moving objects, LaunchRagdoll(Velocity) |
| Gameplay hooks | Plays nicely with health systems and AI | Health-driven mode (only lethal hits collapse), AI paused during reactions, 10 Blueprint events |
| Multiplayer | The server decides outcomes | Server-authoritative impacts, deaths, injuries and limb states; clients replay the impacts |
| Performance | Characters that aren't reacting cost nothing | Idle characters don't tick and hold no motors; per-world simulation budget; visibility and distance gating |
| Developer tooling | Fast to try and tune | Ragdoll Sandbox tab, one-click test level, test director, test dummy, test enemy, presets, debug view, 35 automation tests |
Measured, not promised
Every number measured.
A caught fall lands softer
Head speed when it reaches the floor, from the promo capture. Lower is softer.
<1frame from hit to a committed catch step
35automation tests, all passing on UE 5.5
0tick and motors held by an idle character
10Blueprint events to hook gameplay into
Crowd test
25 to 200 characters, with and without the plugin.
The same crowd was run twice in the editor: once without the component and once with it. Figures are average game-thread time per frame in milliseconds, so lower is better and the comparison between the two columns matters more than the absolute numbers.
| Characters | Standing idle | Moderate hit on everyonedefault budget: 16 stagger at once | Major hit on everyoneall of them ragdoll | |||
|---|---|---|---|---|---|---|
| Without | With plugin | Without | With plugin | Without | With plugin | |
| 25 | 21.4 | 20.9 | 20.4 | 23.2 | 20.7 | 16.3 |
| 50 | 22.3 | 22.2 | 22.1 | 22.4 | 21.9 | 18.8 |
| 100 | 35.6 | 39.3 | 35.4 | 34.7 | 55.4 | 28.6 |
| 200 | 60.5 | 58.5 | 58.2 | 46.1 | 58.5 | 44.0 |
- Idle costs nothing. At every crowd size, zero components were ticking while the characters stood idle, and frame time matched the run without the plugin.
- The budget does its job. With the default simulation budget, 16 characters staggered at once and the rest ignored the moderate hit, so 200 characters cost no more than the crowd on its own.
- Major hits are not capped. All 200 ragdolled together. Average frame time stayed below the run without the plugin, but the worst frames spiked: 94 ms at the 95th percentile.
- Lifting the budget costs real time. Forcing every character to stagger at once took 33.8 ms at 50, 47.9 ms at 100 and 96.1 ms at 200, against 22.1, 35.4 and 58.2 ms without the plugin.
Measured on 2026-11-10 in the Unreal editor on the developer's machine, not in a packaged build. Runs at 100 and 200 characters cover few frames, and the run without the plugin varied between 35 and 58 ms at 100 characters, so read differences of a few milliseconds as noise.
Footage
Captured live in the editor.
Full speed, with the plugin's debug view on. Slow-motion shots are labelled 0.5× replays of the same frames.
All footage uses Epic's mannequin on a grid floor. Severity values visible in the on-screen hit lists were recorded before a later change to how severity is computed; read them as illustrative, not as specs. The 96 vs 309 cm/s comparison is a velocity and stands.
Built for developers
One component. Then tune.
- Enable the pluginCode plugin with source. It builds on Chaos and Epic's Physics Control plugin, with a Physical Animation fallback. No engine modifications.
- Add the component to your characterOne actor component: Physical Impact Reaction. Your character needs a Physics Asset. UE5 and UE4 mannequin bone names work by default and can be overridden.
- Pick a presetGrunt, Default and Tough ship as data assets. Start there, then tune thresholds and strengths.
- Open the Ragdoll SandboxAn editor tab with a one-click test level, a test dummy and a test enemy that throws punches. Watch the debug view while you tune.
- Hook up gameplayTen Blueprint events, a health-driven mode where only lethal hits collapse, and AI that pauses while a reaction plays.
- Ragdoll Sandbox editor tab
- One-click test level
- Scriptable test director and test dummy
- Behavior-tree test enemy that throws punches
- Grunt / Default / Tough presets as data assets
- Debug view with live state and markers
- 35 automation tests
Fired by the component, usable from Blueprint or C++:
- Impact processed
- State changed
- Step
- Settled
- Get-up
- Recovered
- Injury changed
- Protective phase
- Grabbed
- Released
What the markers in the footage mean:
- Yellow sphereCentre of mass
- Red pointCapture point: where balance is heading
- Green ringSupport area under the feet
- MagentaHand target or landing spot
- Red lineBullet path
Ragdoll Sandbox
Every parameter, live while it plays.
One editor tab. Fire something at the test dummy, read what the component decided, change a value and fire again. These are the controls as they appear in the tab.
StateAnimated
Backendidle
Imbalance0.00
Health100 / 100
Composure1.00
Last impacttier, severity (accumulated), bone
Fire at it
Toolbar actions. Press Play or Simulate to fire impactors.
- Build Sandbox Level
- Fire Projectile
- Radial Blast
- Launch Prop
- Sweeping Bar
- Ragdoll
- Kill
- Reset
- Injure Limb
- Heal
- Walk / Stop
- Run Sequence
- Stop Sequence
Build Sandbox Level creates a new map with floor, obstacles, lighting, a test dummy and a director.
Aim it
Quick Fire: where each impactor comes from and what it targets.
- Quick Target Bone
spine_03- Quick Trace Origin
- 600050
- Quick Blast Origin
- 18060-80
- Quick Prop Origin
- 500040
- Quick Sweep Pivot
- 02600
- Trace Params
- group
- Radial Params
- group
- Prop Params
- group
Tune it
Target Reaction: live tuning while playing. Setup maps the component to your skeleton.
- Motor Backend
Auto- Target Mesh Component Name
None- Bone Group Roots
- 7 entries
- Balance Bones
pelvisspine_03- Pelvis Bone
pelvis- Chest Bone
spine_03- Left / Right Thigh Bone
thigh_lthigh_r- Left / Right Foot Bone
foot_lfoot_r- Left Hand Bone
hand_l
Values shown are the defaults for the UE5 mannequin. The panel continues below these rows in the editor.
Where it sits
Five systems. One component.
Hit reaction tools tend to fall into three approaches. Each solves part of the problem.
| Animation-based hit reacts | Ragdoll + get-up | Basic active ragdoll | G.O.A.T. Ragdoll | |
|---|---|---|---|---|
| Reactions differ hit to hit | Authored set | Yes | Yes | Yes |
| Severity tiers | Yes | Rarely | Varies | Minor / Moderate / Major |
| Capture-point balance | No | No | Varies | Yes |
| Procedural catch steps | No | No | Rarely | Yes |
| Protective arms on a fall | No | No | Rarely | Yes |
| Per-limb wounds | No | No | Rarely | Dead arm, limp, clutch |
| Get-up | Animation | Yes | Varies | Aligned to the body |
Columns describe approaches, not specific products, based on a review of Fab listings in this category on 2026-11-07. Individual products vary; check each listing.
Specs
What you're installing.
- Engine versions
- Unreal Engine 5.4, 5.5, 5.7 and 5.85.6 is not supported.
- Platform
- Windows (Win64)
- Delivery
- Code plugin, C++ source included
- Engine changes
- None. One drop-in actor component.
- Name in the engine
- Physical Impact ReactionCode prefix
PIR.
- Physics
- Chaos
- Motor backend
- Epic's Physics Control pluginWith a Physical Animation fallback.
- Skeleton
- UE5 and UE4 mannequin bone names by defaultOverridable for other skeletons.
- Requires
- A Physics Asset on the character
- Self-collision
- CCD on the limbsMissing collision pairs are added to a runtime copy of the Physics Asset; your asset is left alone.
- Authority
- Server-authoritative outcomesImpacts, deaths, injuries and limb states are decided on the server.
- Clients
- Replay the impacts locally
- Ragdoll pose
- Not synced between machinesEach client simulates its own pose from the same impacts, so exact limb positions can differ.
- Grabbing
- Replicated
- Idle characters
- Cost nothingNo tick, no motors.
- Simulation budget
- Per worldCaps how many characters react at once.
- Gating
- Visibility and distance
- Default budget
- 16 characters staggering at onceAs measured in the crowd test; major hits ragdoll regardless.
- Crowd test
- Measured from 25 to 200 characters
- Price
- $79.99 standard licenceUp to $139.99 for the top licence tier. Prices as listed on Fab.
- Store
- Fab listing
- Publisher
- Led the game dev
- Published
- 15 October 2026
FAQ
Before you buy.
Does it work with my skeleton?
It uses UE5 and UE4 mannequin bone names by default, and the names can be overridden for other skeletons. The character needs a Physics Asset.
Does it work with Motion Matching?
That combination hasn't been tested yet, so we won't claim it. The procedural limp is built to work with any Anim Blueprint.
How does multiplayer work?
Outcomes are server-authoritative: impacts, deaths, injuries and limb states. Clients replay the impacts. The ragdoll pose itself is not synced, so two players can see slightly different limb positions for the same takedown.
Why isn't Unreal Engine 5.6 listed?
5.6 isn't supported. The plugin is listed for 5.4, 5.5, 5.7 and 5.8.
Will every hit knock my characters over?
No. Severity tiers decide the response, and a health-driven mode makes only lethal hits collapse. Presets (Grunt, Default, Tough) change how much a character can take.
Do catch steps work on stairs and slopes?
The step logic traces the floor that's actually under the character. All published footage so far is on a flat floor, so judge uneven ground in the sandbox for your own levels.
Is the footage real?
Yes. It's captured live in the Unreal editor with the plugin's debug view on, at full speed; slow-motion parts are labelled replays of the same frames. The key art at the top and bottom of this page is AI-generated illustration, and the scroll sequence is a schematic.
How big a crowd can it handle?
It has been measured in the editor from 25 to 200 characters. Idle characters had no ticking components at any size. With the default budget, 16 characters stagger at once and the rest ignore moderate hits, which kept 200 characters at or below the cost of the same crowd without the plugin. Major hits ragdoll everyone, and 200 simultaneous ragdolls produced frame spikes. The full table is in the crowd test.