Most likely, there is a contract between nvidia and epicgames under which epic promotes RTX technologies. Otherwise, I can’t explain this solution, because there are other game engines where ray tracing is implemented in a different way. As well as baking light and long shader compilation, this is the “last century”. The core of the engine needs to be completely rewritten so that everything is in real time like Unigine. We may be very surprised in UE 5, but so far we only have what we have.)