Xash3D

is a game engine that is almost fully compatible with . The engine can run most games and mods made with GoldSrc, but has significant improvements over the engine.
== Compatibility with GoldSource ==
The compatibility of Xash with GoldSource is estimated to be approximately 90%. This means that the vast majority of mods and games designed for the GoldSource engine should work correctly on Xash3D without any modifications. Numerous single-player mods for the original have been tested on Xash, with most of them functioning perfectly. However, there are some exceptions for games that were designed for the Steam version of , as they utilize undocumented engine features that make their adaptation more challenging (such as VGUI2, SDL2, filesystem_stdio, Steam libraries, and other engine modules).
The engine supports Metamod and AmxModX with their plugins, although not all are fully compatible. Multiplayer mods are also supported by the engine.
== Differences from ==
* Unlike the engine, Xash doesn’t use a modular architecture.
* Xash is written in pure C, while is written fully in C++.
* Pre-caching and on-demand loading of resources.
* Support for BSP maps in formats such as , , and .
* Xash is not bound to the native directory of Half-Life (the “valve” folder), and the mod directory can be specified in the launcher if needed. This allows for the creation of independent games separate from Half-Life.
* Support for ambient maps (Like in games).
* Xash doesn’t require unused WAD files, and resources not used on the loaded map.
* Transparent file system, allowing for accessing files in archives using the same methods as files outside archives.
* Support for colored messages in the console (using the “^” tag).
* Directly changing the sky type and rotation on a map.
* Support for detail textures (as in ).
* Support for HD textures.
* Separate physical and graphical interfaces to provide more functionality and customization.
* More efficient occlusion culling system, increasing FPS and reducing “r_speeds”.
* Extended resource limits that can be customized for mod through the gameinfo.txt file. Reducing limits can save more RAM in mods that don’t require many edicts (server entities). 
**The MAX_EDICTS parameter is also transmitted from the server during multiplayer sessions, allowing clients to automatically adjust to new conditions.
== Engine derivatives ==
Since is distributed under the GNU GPL v3 free license, third-party developers can create forks.
* Sing Engine - first port of original Xash3D to made by adamixik and fire64
* Xash3D FWGS (Xash3D SDL) - a cross-platform fork maintained by Flying With Gauss (a.k.a. FWGS. Formerly SDLash3D). 
**Full support for a large variety of platforms and devices, and includes numerous fixes and extensions to the original engine.
** Unlike the original, it has modular architecture that is similar to and . 
* Xash3DEx (Xash3D Magenta - stillborn project by BlackPhrase. The actual version of this "engine" contains only one .bat file with only five strings.
* Xash3D VR - special version of Xash3D FWGS for Google Cardboard. Was made by Solexid.
* Lambda1VR - special version of Xash3D FWGS for Oculus Quest. Was made by DrBeef.
* Half-LifeX (Xash3Dx) - fork of original Xash3D engine that supports the . Originally was made by marty28.
* Xash3DS - fork of Xash3D FWGS that supports Nintendo 3DS. 
* Xash3D-Wii - fork of Xash3D FWGS that supports Nintendo Wii.
* Xash3D-RT - fork of Xash3D FWGS with real-time path tracing support (via hacks) using OpenGL instead of Vulkan. Made by sultim-t to get an offer by NVidia.
* nightfire-open (Formerly afterburner) - Reimplementation of game engine and SDK that based on Xash3D FWGS engine and hlsdk-portable. Made by noodlecollie
== Software Development Tools ==
Engine has alternative software development kits for modders that have more features than normal Half-Life SDK
* hlsdk-portable - fork of Half-Life SDK with many bugfixes that made to make multiports of GoldSource's mods using Xash3D FWGS. 
* XashXT - fork of that have custom model format, render and physics. Project was abandoned in 2019.
* PrimeXT - fork of XashXT and that have custom advanced renderer, physics using PhysX engine, and modding tools. Currently in development.
* stubserver - Clean Room reimplementation of Half-Life SDK written in pure C. Currently does not have functionality to make mods.
* UMVHLT - Unkle Mike's Custom Build of Vluzacn's Custom Build of Zoner's Half-Life Tools.
* P2Tools - Tools. Includes Vluzacn's Custom Build of Zoner's Half-Life Tools adopted to .
== See also ==
* 
* 
* 
== External links ==
* Official Forum of Xash3D
* ModDB Page
== References ==
# License issues · Issue #63 · FWGS/xash3d-fwgs
# GNU General Public License (Linking and derived works) on Wikipedia
Category:Game engines