Barozi on 19 June 2012
Cheap, proven, easy to develop (and with that many layed off developers have already worked with that, so time saving is also a factor).
As far as I know the UE3 costs $1m to license. Far cheaper than making your own competing engine.
CryEngine 3 is $1.2m.
CryEngine 3 is used by quite a few third party games: http://en.wikipedia.org/wiki/CryEngine#CryENGINE_3
