These guys have always had my interest. A bit skeptical, but than again what they explain in theory is very possible. What are your thought's on their "Unlimited Detail" engine? This is a great breakdown (in the description) of their "Engine".
The things to note though, is there engine is doing things at a much smaller scale than UE4 or other engines in real time. This is also why it looks so basic. Adding things like volumetric lighting etc would be a challenge at best.
Euclideon channel: https://www.youtube.com/user/EuclideonOfficial (https://www.youtube.com/user/EuclideonOfficial)
https://www.youtube.com/watch?v=gM6QkPsA2ds