Half-Life Mod Adds Ray Tracing to 1998 Classic

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Image: Valve

It’s still unclear whether a Half-Life 3 will ever happen, but fans of Valve’s sci-fi shooter franchise can now revisit the original installment with a modern sheen. Software engineer Sultim Tsyrendashiev (sultim-t) has finally released the real-time path-tracing mod for Half-Life that he has been teasing for over a year, allowing PC gamers to re-experience the 1998 classic with ray-traced effects that appear to include vastly improved lighting. According to the installation instructions that can be found on Github, the mod supports DLSS for improved performance.

From sultim-t/xash-rt (Github):


  1. Buy and install Half-Life 1 on Steam
    • A clean installation is preferable
  2. Open its folder
    • In Steam library: right click on Half Life → Manage → Browse local Files
  3. Unzip hl1-rt.zip and hl1-rt-resources.zip into the folder
    • Replace if prompted: so original configs will not interfere with HL1 RT
  4. Run rt_bin/xash3d.exe
    • Press X to switch renderers on the fly

Optional DLSS

  1. Download nvngx_dlss.dll
    • Place it into the rt_bin folder, ensure that it’s called nvngx_dlss.dll
  2. Download RayTracedGL1-Bundle-DLSS.zip
    • Replace the original rt_bin/RayTracedGL1.dll with a new one bin/RayTracedGL1.dll from RayTracedGL1-Bundle-DLSS.zip

Known issues

  • AMD GPUs might have some incompatibility issues
  • Part of the objects are culled by a server before sending packets to a client (and in HL1, even in singleplayer, a local server is created). So some objects might not have proper shadows / be reflected in mirrors / etc, until a server actually sends them
  • Classic renderer doesn’t support dynamic lightmaps (consequently, a flashlight)
  • Classic renderer doesn’t support sky visibility polygons, so some unintended objects might be observed in a skybox
  • Classic renderer’s decals don’t have lightmap lighting
  • Custom maps should work, but the lighting might be overly dark and unplayable; performance on them may be worse
  • Hazard Course is not supported yet

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Tsing Mui
News poster at The FPS Review.

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