UNIGINE
An engine from Tomsk that most people know as the Heaven GPU benchmark — and that in practice is used mainly for simulators and industrial work.
UNIGINE is developed by a company with roots in the Siberian university city of Tomsk. The wider public met it in 2009 through the free Heaven benchmark, one of the first showcases of DirectX 11 tessellation, followed by Valley (2013) and Superposition (2017). They became standard kit for overclockers and reviewers — the kind of advertising most engines can only dream of.
There are games, such as the company's own strategy title Oil Rush (2012), but the main customers are training and vehicle simulators, defence and digital twins. There, a key feature is double-precision coordinates, which let planet-scale worlds exist without geometry starting to jitter far from the origin — a problem Unity and Unreal long solved with workarounds.