"Unifight (or Universal Fight) is a competitive training system with military applications. The competition is formed of two consecutive stages: the first stage is an obstacle course with close quarters battle - any missed obstacle disqualifies the contestant; the second stage is a bout of full contact hand to hand combat." (...) (from Wikipedia)
It appears to include full contact ring fights, knife throwing and firing weapons, and apparently is also "recommended" by its founder for children age 10-11.
The system's founder was Sergey Novikov and I wonder if that is the same Sergey Novikov who was a judo start in the 1970s.
I have no idea about its popularity but it seems that enthusiasm for Unifight is concentrated mostly in Russia and surrounding countries
A scholarly paper was just published focusing on the axiological, ethical and utilitarian benefits of UNIFIGHT. According to the paper Unifight is the most comprehensive combat sports and is allegedly "rapidly developing in many countries" and the 2009 World championships had participation from 40 countries.