Doom 64 Ray Traced Turns Old Hallways into Places That Feel Alive

Doom 64 always stood apart from its PC cousins. Its levels felt tighter, its color palette colder, its soundtrack more unsettling. Now a new free mod gives those same corridors and chambers something they never had before: light that behaves like light.

Doom 64 Ray Traced is an impressive path-tracing enhancement built on top of Doom 64: Retribution, a popular GZDoom conversion that allows you to play the Nintendo 64 game on your PC with Doom II level assets. The designer, jlrouzies-fr, has updated the previous painted lighting and sector brightness with realistic ray-traced illumination. Every lamp, monitor, and lava spot now provides actual light that bounces, softens, and casts subtle shadows on floors and walls.

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When you enter a tight corridor, you will quickly notice the difference. Ceiling fixtures no longer just brighten a flat surface; instead, they create defined pools of light that organically fall off. Walls absorb mild secondary glows from adjacent sources, while gloomy places remain black unless something changes the situation, such as your movement or the appearance of a creature. That’s lot closer to what the original designers must have envisioned when they created the game in 1997, but it’s also clearer and more consistent now.

Moonlight now functions as a directional light source, giving outdoor sections and rooms with sky access a cool wash that casts long, soft shadows from pillars and debris, while the occasional cloud or flash of lightning adds even more variation to the scene, tinting the light and briefly flooding a map with brighter flashes. You’ll also notice that the per-map fog is now a genuine 3D effect that lighting can pass through, allowing you to see shafts of light cutting through the haze and dust motes drifting inside those shafts. Water surfaces now emit projected caustics, while lava glows and breathes with a sluggish heat field.

Combat and monsters receive the same treatment. Enemy eyes shine with their own small light sources, allowing them to be seen in low light without washing out the entire room. Lost Souls only light up when they are burning, which is a great touch, and blood remains on the floor after a kill and varies in color based on the monster you killed. Projectile leave nice scorch or electric marks, while sparks and debris fly off surfaces with proper normals. Exploding barrels also scatter curved plates that settle and leave burn marks, and to top it all off, there is now a functional flashlight that utilizes a warm beam and drains batteries, complete with authentic flicker and burnout sounds in newer versions.

The mod is packaged as a modified GZDoom build with the RTGL1 path-tracing renderer. You’ll need a legally obtained copy of Doom II IWAD, Doom 64: Retribution version 1.5, and the corresponding OGG soundtrack pack. When you first run it, the launcher will check your files and start the game. Just keep in mind that you’ll need a GPU that supports ray tracing, such as an NVIDIA RTX, AMD RDNA 2 or newer, or Intel Arc. There’s also the option to employ DLSS or FSR upscaling to make the frame rates playable, and the mod is still in active beta, with ongoing work to tackle bogus emissives, stuttering, and lighting issues.

The current build is available on the mod’s GitHub page, jlrouzies-fr/doom64-rt. Simply point the launcher at your files and return to those familiar levels, which still resemble Doom 64, but they appear more solid, present, and difficult to forget once the lights go down.