Unigine used to be very expensive, CryEngine difficult to master. In the meantime Unigine got cheaper and there was a lot of work to make CryEngine more accessi

Unigine used to be very expensive, CryEngine difficult to master. In the meantime Unigine got cheaper and there was a lot of work to make CryEngine more accessible, so that might explain popularity of Unity (easy to learn) and Unreal ("golden standard" allowing AAA games with great developer backing).