What is built today

Version 0.3.0 (Looks and ease) is in progress. Everything below works now; planned work says so.

Version: 0.3.0 (Looks and ease), in progress
Engine: 21 crates of Rust, no third-party crates
Content: 33 example projects and five templates
Platform: Windows 10 and 11, a GPU with Vulkan 1.3

The agent interface

A game is a folder of plain-text files. The agent reads scenes, prefabs, materials, scripts, UI and animation graphs, then changes them with spx. The tool prints text in a terminal and JSON to a pipe.

Every change is a logged command and can be undone. If two agents, or an agent and a person, edit one project, they get a conflict instead of a silent overwrite. Each error has a stable code, a location (file, line and column) and a fix.

spx docs prints the manual offline. Each new project includes an AGENTS.md that tells an agent how to work in it.

prefabs/coin.prefab

# Made by `spx model import` from coin.glb: 0.5 x 0.5 x 0.14 m.
# Collider: a box around it, 0.5 x 0.5 x 0.14 m.
format = 1
[[entity]]
id = "coin"
[entity.Transform]
[entity.MeshRenderer]
mesh = "models/coin.glb"
[entity.Collider]
shape = "box"
size = [0.5, 0.5, 0.14]
offset = [0, 0.35, 0]
[entity.Animator]
clip = "Spin"

A whole prefab: a model, a box collider and a spin clip, and nothing else.

Studio

spx studio is the window for a person in the same project. It shows the game, the scene tree, an inspector, the console, the tests and a profiler, with a command palette. A terminal beside the game runs a command-line agent.

The Studio uses the same commands an agent uses, so a change made by hand and a change made by the agent land in the same files.

A full visual editor is planned.

The Superposition Studio: a dark window with the village scene in the viewport, the scene tree and inspector on the left, and the console, tests and profiler tabs below — The Studio, with the village example open.

Rendering

The renderer is physically based and runs on Vulkan 1.3. It has cascaded sun shadows, clustered point and spot lights with shadows, and a physical sky with named presets. It also has sky reflections, ambient occlusion, bloom, fog, colour grading, auto exposure, AgX tonemapping and quality presets.

Levels of detail, instanced batching and culling are included, with 2D sprites, render-texture cameras and screenshots.

A forest clearing of low-poly broadleaf trees, pines and grey rocks under a blue sky, with long shadows — The scenery example.

Physics

The physics is a deterministic rigid-body solver. Shapes include boxes, spheres, capsules, convex hulls, meshes and height fields, plus compound colliders. Joints are fixed, hinge, slider, ball, distance and spring.

It also has continuous collision, sleeping, triggers, and ray, shape and overlap queries. A capsule character controller, ragdolls and hitboxes are included.

A robot in a dirt yard of crates, barrels and stone pillars, with a white windmill behind — The windmill errand example.

Animation

Animation covers skinned models, clip blending, and animation graphs with state machines and masked layers. It includes two-bone IK, foot placement and look-at, root motion, morph targets, clip events, clips shared between characters, and timelines that animate a field.

Audio

The engine reads WAV and Ogg Vorbis with its own decoders. Buses have a limiter and ducking. Sound can be positional, with voice stealing and sound groups. Output is low latency on Windows.

A character at a night campfire with flames, rising smoke and warm light on the ground, and a Poke Fire button — The audio example: a night campfire.

UI and effects

Game UI is data: screens and a theme, with keyboard, mouse and gamepad navigation, and sharp text at any size. A script canvas draws a custom HUD. Particles run on the GPU, and decals are projected.

The 2D platformer template: an orange hero on green ground with pickups, a floating platform, a pit and a score counter — The 2D platformer template.

Scripting

SPX Script is a strict subset of TypeScript, with its own compiler and virtual machine. Scripts use behaviours, events, async waits, tweens and state machines. Hot reload keeps values.

A sandbox limits CPU and memory, so a script error does not take the engine down. Type definitions are generated from the engine.

Gameplay systems

Navigation is baked from the colliders, and paths use A*. The engine also has perception and noise, projectiles, interactables, input actions with recording and replay, gamepads and save games.

A small 3D village: timber and brick houses, a well in the plaza, villagers, a red brick windmill and a forest behind, with a quest line and a counter on screen — The village example.

Tools

spx view plays a game, with a terminal beside it if you want one. spx build makes a standalone Windows executable. The tool also imports models, generates textures from a seed, compares golden images and profiles a run. spx connect writes the files an agent needs.

Five templates are included: 3D, 2D, a 2D platformer, a 2D top-down arena and a 3D shooter asset kit. 33 example projects ship with the engine.

The default 3D project: a sunlit stone platform with a gateway and a bronze sphere on sand — A new 3D project, before you change anything.