A modder has taken up the real-time path traced torch of putting ray tracing into the original Half-Life, planning for a release in 2022—that is, this year. Russian modder sultim_t dropped a teaser of how Half-Life with ray tracing looks in action on YouTube, and says they'll release both the full build and source code when it's ready.
Ray tracing will calculate global illumination, allowing detailed reflections, refraction, soft shadows, and detailed visual effects from lighting. Sultim_t's work builds on previous work by other modders to bring Vulkan ray tracing to Xash3D, an engine for modding Half-Life's engine. Impressive mods like this are, as always, an iterative, time-consuming process.
For my part, I love the vibe on old games like this that add ray tracing. It's that first demo of Quake 2 with ray tracing back in 2019 that really got me excited about the aesthetic of it. Something about those crisp, modern reflections and lighting combined with the old lo-res textures and polygons establishes a precise aesthetic I can't help but love. In a way, it's a bit like seeing an old, dirty painting restored to its former glory.