Unreal Engine
Used by 9 peopleunrealengine.com ↗

“After several years at Electronic Arts on the Frostbite team, I very recently joined Epic Games' Unreal Engine team.”
Ludovic Chabant Interview, Software developer (Epic) · via Uses This 
“Currently I work with the Unreal Engine, one of the most popular for making games these days.”
Derek Chatwood Interview, Game designer, illustrator · via Uses This 
“Unreal 3 - Epic has big offices here in China, provide great support for their software, and are friendly to our studio.”
American McGee Interview, Game designer · via Uses This