Thistle is an AI-built game engine — an explicit experiment in whether an AI can build something a beginner can actually pick up and use, not just something technically impressive. Existing engines in this space have a real reputation for the opposite: Cocos2d alone ships three incompatible codebases under one name (Cocos2d-x, Cocos2d-js, Cocos Creator), and its old project-generator CLI required Python 2 — dead since January 2020, and gone from macOS entirely. The bar this project is trying to clear isn't "does it render a triangle," it's "would a beginner's first hour with this be spent making something, or fighting the tooling."

A small, simple, cross-platform C++ game engine for 2D and 3D games, built on the sokol renderer, with Box2D and (opt-in) Jolt physics, miniaudio audio, fontstash text rendering, realtime networking, and in-app purchases — plus a thistle command-line tool for scaffolding, building, and running a project, and a 3D level editor. The entire public API is a single umbrella header, thistle.hpp — #include it and you have everything; the engine itself compiles to one thistle CMake target you link against (not literally header-only in the no-linking sense, since it's more than a handful of one-liner functions, but there's exactly one header to ever look at).

• Graphics: Metal (iOS/macOS), D3D11 (Windows), GLCore (Linux), GLES3 (Android, Web) — all through sokol_gfx/sokol_gl.
• 3D (thistle::three): a lit renderer with models from glTF/GLB and OBJ, sun shadows, point and spot lights, sky and fog, instancing, particles, terrain, skeletal animation, block worlds (Minecraft- or Teardown-style, endless or not, MagicaVoxel import), 3D sound, and a built-in character controller. Run on Windows with a real GPU (D3D11) and on Linux's software renderer; not yet on a Mac — see docs/3d.md.
• Physics: Box2D for 2D; Jolt for 3D rigid bodies and Teardown-style voxel destruction (opt-in, docs/physics3d.md).
• Debug UI: Dear ImGui windows for tuning and stats (opt-in).
• Audio: miniaudio.
• Text: fontstash.
• Networking: async HTTP (NSURLSession/WinHTTP) plus a Mirror-flavored realtime client/server layer — synced fields, Commands, ClientRpcs — over TCP, and multiplayer block worlds on top of it.
• Dedicated servers: a headless engine (thistle_server) that builds on a bare VPS, and DedicatedServer: a console to type commands into (kick 3, list, your own), settings in server.json, a log, passwords, max players, and a clean stop that saves. thistle new --template multiplayer is a game and its server. See docs/dedicated-servers.md.
• In-app purchases: StoreKit (iOS/macOS).
• Minor 3D: the older perspective drawing mode on Frame (camera3d, cube, sphere3d, mesh3d...) layered on the 2D renderer with one fixed light. It still works; new 3D games should use thistle::three.

See docs/ for the real documentation — building, drawing, 3D, physics, networking, in-app purchases — written with the actual limitations spelled out, not glossed over.

Almost every line here (~99%) was written by Claude (Anthropic's AI), directed and verified at every step by a human who tested on real hardware, actually ran things instead of assuming they worked, and pushed back whenever something was hand-wavy. That's not a disclaimer tucked at the bottom of the page — it's the actual premise of the project: this is what an AI building real infrastructure looks like when it's held to a real "does it actually work" bar instead of "does it look plausible." Judge the code on that basis, and check docs/ for the places this project is honest about where that bar hasn't been fully cleared yet.

curl -fsSL https://raw.githubusercontent.com/StacikM/thistle/main/install.sh | bash
thistle new mygame && cd mygame && thistle run
thistle new myshooter --template fps     # or third-person, or voxel: a 3D game to start from

On Windows, download install.bat and run it locally (same defaults, no one-liner published yet).

Installs the engine and the thistle CLI (see docs/cli.md) — no dependencies to fight, standard library only.

macOS is the recommended OS to develop on. The core engine was written on a Mac, so that's where the 2D engine, the Metal backend, StoreKit purchases, and the thistle CLI have had the most real use, and it's the only OS that can build for iOS. Windows and Linux are supported and CI builds and tests on all three, but they came later.

The one exception is 3D: thistle::three hasn't been run on a Mac yet. It has been run on Windows with a real GPU (D3D11) and on Linux's software renderer, so if 3D is what you're making, use Windows for now. See docs/3d.md and docs/building.md for what's been verified where.

cmake -S . -B build
cmake --build build --target thistle

Requires a consumer project (game) that adds this as a subdirectory and links against the thistle target — see docs/building.md if you're not going through the CLI. -DTHISTLE_BUILD_SMOKETEST=ON builds the example programs in examples/ (the 2D smoketest, the 3D demos: voxel_demo, forest_demo, terrain_demo, animation_demo, model_viewer and more), the templates, and the headless tests ctest runs.

A 3D level editor for thistle::three: place models, shapes, lights, trigger volumes and spawn points with move/rotate/scale gizmos, group them, give them properties your game reads, paint block objects (voxels) with brushes and a box tool, bring in models and MagicaVoxel files by dropping them on the window, set the sun, sky and fog, with undo for all of it. Levels save as .scene.json in your game's assets/scenes/, and the game loads them with three::Scene3D (docs/scene3d.md). It starts on a projects screen: recent projects, New project (the templates, as a form), and Open folder, which checks it's a Thistle project and offers to make it one. Build & run builds and starts the game from inside the editor. It's drawn with the engine itself, not ImGui. See tools/thistle-editor for how to use it and exactly what's been tested.

thistle editor install   # build it and put `thistle-editor` on your PATH
thistle editor update    # pull the latest engine source, rebuild, reinstall
thistle editor run       # build (if needed) and run it on the project you're in, without installing

See AGENTS.md — repo layout, conventions, and the one rule that matters most here: don't claim something works unless you actually ran it.

MIT — see LICENSE.