Halo Reach has barely been available on PC for any period of time, but already it has ray tracing. OK so it's not official, but the Reshade post-processing effect known as path tracing, is as close to ray tracing as you can get without Nvidia accelerated hardware and it still looks fantastic. Halo Reach was already a great looking game and with a little help from path traced lighting, it looks even better.
Nvidia introduced the concept of real-time ray tracing to a lot of gamers, where many believed it would be at least a decade before we'd see such lighting effects commonly found in games. With hardware acceleration, though, it made it possible for the first time for many. Except, there are still very few games which natively support it, and not many people with the hardware to run it at decent frame rates and resolutions.
This demonstration video shows how it adds some lovely volumetric lighting effects to scenes, improves shadows, adds depth and character to environments when colored light sources are present, adn adds details to the character's weapon and gloves forearm. Indoor environments with artificial lighting can benefit tremendously.
The best part of all this is it's hardware agnostic and not too intensive. So you can enjoy this ray traced effect whether you have a mid-range GPU or higher from either AMD or Nvidia.