According to Crytek CEO Cevat Yerli if you want your game engine to run 100% in real time then your only option is the CryEngine.
Speaking in an interview with Develop Yerli said that the studios engine is the only one “on the planet that runs in 100% real time.
“CryEngine is the engine you consider when you think of next generation development,”
We are actually the only engine on the planet, including Unity and Epic, that is 100 percent real time,” said Yerli. “People underestimate what it means to be 100 percent real time.”
“there are games that are developed with CryEngine that you just cannot develop with the Epic and Unity engines”.