Enterprising developer Pascal Gilcher, best known for creating a ReShade add-on for ray-traced global illumination (RTGI), has unveiled his work on a path-traced version of Skyrim Special Edition. Even more excitingly, this new ReShade add-on operates on similar principles to Nvidia's RTX Remix, with the potential to add world-space (rather than screen-space) path-traced lighting to thousands of games based on DirectX 9 or later.
This new PTGI upgrade is significantly easier to implement than RTX Remix, which requires a good amount of coding to implement. Pascal, in contrast, promises "a little bit of clicking around in the [interface]" that works in pretty much any DX9+ game that the ReShade plugin can operate in.
Behind the scenes, Pascal says that the add-on works by grabbing pretty much all calls to the graphics card no matter their parameters, in a similar manner to debugging tools like NSight or RenderDoc. From here, you can pass the data to the shaders and do your own things with it; getting the special world-space path tracing shader to work just requires sending it the appropriate input data for the game it's running in, a process that can take anywhere from 10 minutes to two hours.