Simplified physics package for Unity ECS, built for large-scale systems. Simulation can be tuned toward throughput, or toward bit-stable determinism.Little Physics is a Unity ECS physics package for large-scale simulations. Pause or speed up the simulation, use dynamic, static, kinematic, and trigger bodies, and tune LOD for simulation accuracy. A spatial map limits object-to-object collisions to a volume you define. The package supports directional and radial gravity, friction, and custom job interfaces for collision detection and linecasts.With ECS, Burst, and multithreading, it can handle on the order of 1,000,000 entities. It suits low-determinism workloads such as crowds, liquids, and particles — not highly deterministic simulations.FeaturesDeep simulation tuning — separate fixed and variable settings for different simulation profilesLOD — up to four levels with per-level limitsTime control — pause, slow down, or speed up (0, 1, 2, or 4 time scale)Body types — dynamic, static, kinematic, and triggersGravity — directional and radialFriction and surface collisions — every dynamic body is tested against surfaces each frameSubsteps — split a fixed update into 1–4 substeps for better penetration handling and stabilityCollision detection and linecast — hook into the pipeline via public job interfaces and system groups.RequirementsUnity 6000.0 or newer.com.unity.entities 1.4.8 (required). Declared in package.json and installed through the Package Manager.Sample scenes also require com.unity.entities.graphics and com.unity.inputsystem.RequirementsUnity 6000.0+ (Unity 6)Entities (com.unity.entities) 1.4.8Platforms: Android, Web, Desktop(iOS and consoles not yet tested)Render pipelines: URP, HDRP, Built-inBuilt for crowds, particles, and liquids — cases where scale matters more than perfect frame-to-frame determinism.FeaturesPause and speed up the simulation up to 4×LOD for simulation quality (higher detail near the camera)Dynamic, static, kinematic bodies, and triggersFriction and surface collisions1–4 substeps per fixed update for better penetration handling and stabilityCustom jobs — hook into the pipeline via public job interfaces and system groupsLimitationsDeterminism decreases with loose LOD and simulation settingsMaxEntitiesCount caps how many entities participate; excess entities are ignoredDynamic bodies: spheres onlyStatic and kinematic bodies: spheres and capsules onlySurface shapes: sphere, inverse sphere, infinite plane (identity rotation), box (identity rotation)Time scale supports 0, 1, 2, and 4 onlyFor a deeper understanding of a package, please follow a documentationCode generation with Cursor
