Enthusiast writes a new renderer for Doom 3 BFG Edition from scratch and shows path tracing with DLSS 5

NVIDIA's neural rendering has reached Doom 3 sooner than most modern releases. A developer going by the nickname ruisu_enjeru has published a video on YouTube demonstrating v0.2 — a graphical overhaul of Doom 3 BFG Edition with real-time path tracing. According to them, a completely new renderer was written from scratch for this; the build supports DLSS 5 and DLSS Ray Reconstruction.

There is no public version yet, and the author gives no dates. They describe the project as far from a final state: a significant part of the original's content has already been reworked for the new renderer, but much still has to be ported, redone or fixed. “There is still a huge amount of work ahead: many systems, materials, lighting, characters, effects and other content need to be ported, reworked or fixed,” says ruisu_enjeru.

The renderer has been replaced entirely

The difference from the usual graphics mods lies in the approach. A typical retro upgrade is a pack of high-resolution textures, rewritten shaders and post-processing on top of the stock idTech 4 pipeline. Here the original renderer is replaced with a different one built around path tracing, and the game content is adapted to it. This route costs more effort, but it removes a limitation of old engines: lighting in Doom 3 was built on pre-placed light sources and on artists' decisions, and physically correct light cannot be added “on top” of that.

The bulk of the work goes into moving assets and materials over to the new lighting model — this is exactly what the author names as the reason it is too early to release the build.

The video shows the contribution of Ray Reconstruction most clearly: the noise artifacts typical of path tracing are almost invisible, and the lighting looks noticeably better. The gain from DLSS 5 itself is harder to make out in the video.

Doom 3 is being modernized in more than one project

In April 2026 there were reports of another development that added real-time path tracing to Doom 3. Two independent projects around a single engine within one half-year indicate that idTech 4 has proved a convenient platform for experiments: games on it are compact in geometry and work with clearly separated light sources, while the difference in lighting is easy to see. ruisu_enjeru's build cannot be downloaded yet — only a video demonstration of the current state is available.

Why DLSS 5 showed up in a mod before official games

DLSS 5 has not been officially released yet. An unfinished version of the technology has leaked online, and the “on/off” comparisons made with it have already sparked arguments: critics say that AI redrawing changes the characters' appearance and interferes with the developers' artistic intent. In terms of the heat of the discussion, the technology is being compared to the arrival of real-time ray tracing on GeForce RTX 20-series graphics cards.

Against this backdrop the situation looks natural: official integration requires patches, testing and approvals from publishers, while an enthusiast only needs their own renderer, into which the library is plugged directly. The modding community has probably turned out to be faster once again, as was already the case with previous generations of ray tracing.

For the industry, this also implies a higher bar of expectations for official remasters: if a single developer brings a twenty-year-old game up to full path tracing with neural denoising, there will be more questions for paid re-releases. At the same time the barrier to entry is rising for the enthusiasts themselves — such projects have shifted from reworking textures to writing renderers, and that is a task at the level of a graphics programmer. If the trend holds, retro modifications will increasingly depend on the availability of people with skills in real-time rendering and tracing.