With its twelve-year-old engine (not counting the years of development) GTA IV is visually dated to say the least. No worries, with time and talent, a moder has switched the map of GTA IV in the GTA V engine while adding Ray Tracing.
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Ray Tracing can work miracles, proof again with this video from Digital Dreams, which you can see above. It allows you to admire the city of Liberty City with the engine GTA V, all with the famous technology of Ray tracing
In the video in question Digital Dreams uses a fairly basic configuration of Ryzen 7 1800X processor, GTX 1080 Ti MSI Armor and 32 GB RAM. If you also want to have fun, you will have to scrupulously follow the steps that are given in the second video above.
When we see what the Ray tracing in such a game, we can obviously think without getting too wet that it is indeed the future of video games in terms of graphics. Even if in this precise case, the effects are far from being optimal (at the level of the reflections at least).