FOnline Engine

FOnline is a reusable C++20 engine for isometric Fallout/Arcanum-style games. It is normally embedded as a git submodule inside a game project; the game project provides content, scripts, configuration, native extensions, presets, and packaging policy.

Start Here

• Docs/README.md - maintained engine documentation map.
• AGENTS.md - AI-maintainer entry point and repository conventions.
• PUBLIC_API.md - public API notes.
• TUTORIAL.md - tutorial for using the engine.
• Source/README.md - source-tree overview.
• Source/Tests/README.md - engine unit-test suites.
• BuildTools/README.md - build tooling notes.

Repository Layout

• Source/ - engine source code: applications, client/server runtime, scripting, resource pipeline, tools, essentials, and tests.
• BuildTools/ - CMake/tooling scripts for building, code generation, packaging, and platform workspace preparation.
• Resources/ - engine-owned runtime/build resources.
• ThirdParty/ - vendored third-party dependencies.
• Docs/ - maintained engine docs that were split out of game-project documentation.

Using the Engine From a Game Project

A game project typically:

1. Adds this repository as Engine/ submodule.
2. Provides a root CMakeLists.txt, CMakePresets.json, and .fomain configuration.
3. Provides game scripts (Scripts/), content (Critters/, Items/, Maps/, Dialogs/, Texts/, etc.), and optional native extensions (SourceExt/).
4. Builds final targets through the engine BuildTools and project-specific target definitions.

Last Frontier is one such embedding project. Engine docs may use ../../... paths when they intentionally point from Engine/Docs/ back into the embedding project.

Key Maintained Docs

• Docs/ClientUpdater.md - client host/runtime split, runtime ABI, updater protocol, and server-side update backend.
• Docs/Debugging.md - native debugging, stack traces, Visual Studio helpers, and validation notes.
• Docs/Nullability.md - script/native nullability contract and analyzer workflow.
• Docs/MapperTools.md - mapper automation and native mapper helper integration points.
• Docs/WebDebugging.md - web target build/debug workflow.
• Docs/AndroidDebugging.md - Android target build/debug workflow.

Validation

Use the embedding project to exercise real targets. In Last Frontier, the common engine baseline is the LF_UnitTests / RunUnitTests target, with platform-specific package/build validation for BuildTools and runtime changes.

About

• Site: https://fonline.ru
• GitHub: https://github.com/cvet/fonline