Open-source game development SDK for creating mods and games using Valve's Source 1 engine.
Source SDK 2013 is the official development kit for Valve's Source 1 game engine, providing the complete source code for Half-Life 2, Half-Life 2: Deathmatch, and Team Fortress 2. It enables developers to create custom game modifications (mods) and standalone projects by building upon these established game foundations. The SDK integrates with the Steam platform for both development and distribution of mods.
Game developers and modders who want to create custom modifications for Source 1 engine games or develop new games using Valve's established engine technology. This is particularly valuable for those targeting the Steam platform for distribution.
Provides direct access to Valve's professional game engine source code, offering a robust foundation for mod development that maintains full compatibility with the Steam ecosystem. Unlike generic game engines, it comes with complete implementations of popular Valve titles ready for modification.
The 2013 edition of the Source SDK
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Includes full source code for Half-Life 2, HL2: Deathmatch, and Team Fortress 2, providing a professional-grade foundation for mods without starting from scratch.
Automatically builds against Steam Runtime for Linux, ensuring seamless compatibility with Steam's ecosystem for both development and distribution.
Offers build scripts for Windows (Visual Studio) and Linux (Podman), supporting development on multiple operating systems with clear instructions.
Provides direct links to Valve's partner documentation for distributing mods on and off Steam, streamlining the publication process.
The SDK is licensed only for non-commercial use under the SOURCE 1 SDK LICENSE, severely limiting its utility for commercial game projects.
Based on the Source 1 engine, which lacks modern features compared to newer engines like Source 2 or Unreal Engine, and may have compatibility issues with contemporary hardware.
Requires specific tool versions (e.g., Visual Studio 2022, Python 3.13) and a Steam installation, creating a steep initial setup barrier for newcomers.