Cooler2/ApusGameEngine: An open source Delphi/Pascal game engine · GitHub

Cross-platform 2D/3D game engine written in Delphi/Pascal by Ivan Polyacov (Apus Software). In active development since the early 2000s, used in several commercial titles.

Engine 5 supports five platforms: Windows, Linux, macOS, Android and iOS — up from Windows and Linux in Engine 4.

Games made with this engine:

• Astral Masters — Windows, iOS (Engine-2)
• Spectromancer — Windows, iOS (Engine-2.5 (late))
• Astral Towers — Windows, Linux, iOS (Engine-3 / 4)
• Astral Heroes — Windows (Engine-3)

The engine is written in standard Object Pascal and compiles with both Delphi 11+ and FPC 3.2+ from a single codebase, with no conditional forks for compiler-specific syntax. This is a deliberate design constraint: language features that work in one compiler but not the other are avoided. The goal is long-term portability — the same source should remain buildable regardless of which Pascal toolchain you use or what platform you target.

This means: no inline variables, no type inference, no attributes, no anonymous methods beyond what both compilers support. Compatibility is not a limitation to work around — it is part of the design.

Base library (Base/Apus.*.pas) — platform-independent utilities that can be used without the engine:

• Math: vectors, matrices, quaternions, geometry (2D/3D), spatial primitives
• Strings: UTF-8 (String8) as the primary string type, with full helper API
• Collections: hash maps, arrays, containers, sorted structures
• Animation: tweening, animated values
• I/O: file handling, compression, image loading/saving, cryptography
• Network: TCP, HTTP requests
• Platform: threading, logging, profiling, clipboard, cross-platform time

Engine (Apus.Engine.*.pas) — the game engine itself:

• Scene system with defined lifecycle (Load → Init → Process → Render)
• UI system: widgets, layout, CSS-like style system, event signals
• OpenGL renderer (GL 3.3 core baseline, GLES 3.0 for mobile targets; newer GL features only as optional extension-gated fast paths): 2D/3D drawing, shaders, textures, nine-patch, text
• Resource management with reference counting
• Audio (BASS, SDL, IMX backends)
• Platform layer: Windows, Linux, macOS, Android and iOS
• Multi-window and DPI-aware display support

The current stable version is engine4. It is used in shipped games and is the recommended starting point if you want something that works today.

→ Download engine4 releases
→ Documentation / Tutorial

engine5 is a major refactoring of the entire codebase. APIs change frequently. Nothing here is guaranteed stable. It is not yet suitable for starting a new project.

What's being worked on is tracked in engine5_feature_roadmap.md. Current highlights:

• New foundation library (Apus.Core, Apus.Strings, Apus.Conv, Apus.Log, Apus.Threads, …) replacing the monolithic legacy Apus.Common
• OpenGL core profile pipeline with a GL 3.3 desktop baseline and a shared GLES 3.0 mobile path
• CSS-like style system for UI (declarative, inherited, state-aware)
• Geometry library overhaul: single-precision first, spatial primitives, intersection and culling tests
• Multi-window support with runtime DPI changes
• Robot API for automated testing and tooling integration (file-based protocol, UI introspection, screenshot/pixel commands)
• CI coverage on Windows, Linux and macOS arm64 (GitHub Actions)
• Modernized demo suite, including the touch-oriented TouchDemo used for mobile bring-up

Build notes and platform-specific tooling live under platform/. Engine5 has an evolving manual under manual/ and detailed implementation status in the feature roadmap; both are works in progress.

License: BSD-3 — see license.txt; third-party components and their notices are indexed in THIRD-PARTY.md
VK group: https://vk.com/apusgameengine