Tagline: A Rust 2D game engine designed with agent-assisted game development in mind from the beginning. Build professional games with AI agents or by hand with a sane API and traditional code -- your choice.
Reality: I started learning Rust and then I decided to start building a 2D game engine to apply the language; all while using agentic tools.
Should you use this engine today? Probably not -- it's constantly evolving and is one big experiment. Use at your own risk.
# Windows
git clone https://github.com/Kersheh/ryo2d.git
cd ryo2d
./install # Windows
./install.sh # macOS / Linuxryo2d init my-game
cd my-game
ryo2d devWhen you run ryo2d init, you'll be prompted to install Agent Skills—domain-specific knowledge that helps AI assistants understand the engine's APIs and patterns. This is highly recommended for agentic game development.
| Command | Description |
|---|---|
ryo2d init <name> |
Create a new game project |
ryo2d build |
Build production release |
ryo2d run |
Run the production build |
ryo2d dev |
Development mode with hot-reload |
ryo2d export |
Package release into distributable zip |
ryo2d install-skills |
Add Agent Skills to existing project |
ryo2d netplay |
Test multiplayer with friends over internet |
New projects include optimized dependencies for playable dev builds. If you're upgrading an existing project or experiencing slow dev builds, add this to your Cargo.toml:
[profile.dev.package."*"]
opt-level = 2This optimizes dependencies (physics, rendering) while keeping your game code fast to compile. ryo2d dev will warn you if this is missing.
- ECS — Entity-Component-System with generational IDs and archetype storage
- Scene Management — Stack-based scenes with transitions
- Event Bus — Decoupled publish-subscribe communication
- Object Pooling — Pre-allocated entity pools for bullets, particles, effects
- State Machines — Generic FSM and state stack for player states, AI, menus
- Sprites — GPU-batched rendering with z-ordering and per-sprite shaders
- Animation — Sprite sheets, state machine controllers, 24 easing functions
- Skeletal Animation — Bone hierarchies, per-bone keyframe tracks, crossfade blending, FSM controllers
- Tweening — Transform tweens, generic property tweens, sequences, 24 easing functions
- Parallax — Layered scrolling backgrounds with infinite scroll
- 2D Lighting — Point lights, spotlights, volumetric effects, atmospheric scattering
- Shadow System — Hard shadows, soft shadows, ray-marched shadows, drop/blob/contact shadows, ambient occlusion
- Trails — Motion path rendering with fade and taper effects
- Particles — GPU-batched particle system with emitters, attractors, and presets
- Raycasting — GPU-accelerated pseudo-3D rendering (Wolfenstein/Build engine style) with dynamic lighting, smooth lightmaps, and sprite illumination
- Post-Processing — Shader pipeline (CRT, vignette, chromatic aberration, etc.)
- Rapier2D — Full physics simulation with rigid bodies
- Collision Shapes — AABB and circle colliders with trigger support
- Collision Events — Started/stopped events for gameplay logic
- 2D Camera — Follow targets, zoom, rotation, bounds
- Screen Shake — Trauma-based shake with smooth noise
- Keyboard & Mouse — Key states, mouse position, scroll
- Gamepad — Controller support via gilrs (buttons, sticks, triggers)
- Time Scale — Slow-motion and fast-forward effects
- Hitstop — Freeze frames for impact feedback
- Kira Backend — Music and sound effects with volume control
- Hybrid System — Immediate mode for HUDs, retained mode for forms
- Widgets — Buttons, text input, dropdowns, sliders, checkboxes, scroll views
- Layout — HBox, VBox, Stack containers with alignment
- Theming — Centralized styles with hot-reload support
- Pathfinding — A* with nav agents and grid-based navigation
- Procedural Generation — BSP dungeons, cellular automata, WFC, noise
- Inventory System — Item registry, slot-based containers, equipment, loot tables
- Client-Server — Dedicated and listen server modes
- Transport Layer — UDP (LAN) or WebRTC (internet with NAT traversal)
- Replication — Automatic entity/component synchronization
- RPCs — Remote procedure calls with targeting
- Netplay Testing —
ryo2d netplayfor quick multiplayer testing
- Save System — 3-tier saves (system, world, game) with compression
- Configuration — TOML-based project settings, JSON user preferences
- Hot Reload — Asset changes apply without restart
- Debug Visualization — Colliders, velocities, origins, FPS overlay
- Profiler Window — Real-time flamegraph with CPU/GPU timing (requires
--features profiler) - Logger Window — Live log viewer with level/context filtering
| Crate | Purpose |
|---|---|
| hecs | Entity-Component-System |
| rapier2d | 2D Physics |
| wgpu | GPU Rendering |
| winit | Windowing |
| kira | Audio |
| image | Image loading |
| puffin | Profiler instrumentation |
Build and view the documentation locally:
# Build HTML docs (mdbook guide + rustdoc API)
./build-docs.ps1 # Windows
./build-docs.sh # macOS / Linux
# Open in browser
start docs/book/index.html # Windows
open docs/book/index.html # macOS
xdg-open docs/book/index.html # LinuxNote: These docs have been auto-generated by agents throughout the process without indepth review but architecture has changed and shifted wildly throughout while possibly missing out on updating it; it may be inaccurate or confusing.
MIT