Just Unknown

Just Game Engine

A 2D game engine for Flutter that thinks in systems.

Explicit ECS, a fixed-timestep simulation core, and 20+ subsystems from physics to dialogue. Open source under BSD-3.

DocumentationExamplesGitHub

By the numbers

34+Built-in components
17+Built-in systems
15+Easing curves
6Platforms via Flutter

Get started

One dependency away

Add the package, create a world, register systems, run.

flutter pub add just_game_engine
Quick start guide

Subsystems

Everything a 2D game needs, nothing bolted on.

Explicit ECS

Entities are ids, components are data, systems run in a declared order. Predictable, cache-friendly, serialisable.

Fixed-timestep loop

Deterministic simulation steps with render interpolation, so gameplay stays stable when phones throttle.

Physics & collision

Rigid bodies, collision detection, ray casting and ray tracing through just_physics_engine.

Particles & effects

Deterministic particle systems and effects that replay identically for multiplayer.

Sprites, atlases, animation

Batched sprite rendering, sprite atlases, frame animation and 15+ easing curves.

Tiled maps & scene graph

Load Tiled maps directly, compose scenes with a scene graph and parallax backgrounds.

Post-processing shaders

Fragment shaders and post-processing passes on the 2D canvas.

Audio engine

Multi-channel mixing with just_audio_engine, ready for music, SFX and ducking.

Input

Keyboard, mouse, touch and gamepad through one input manager.

Yarn Spinner dialogue

Yarn Spinner 2.x scripts for branching dialogue and narrative.

Localization

Localization with fallback chains built into the asset pipeline.

Asset management

Async asset loading, caching and hot reload friendly workflows.