#2 Arthias
Arthias is a mod which intends to push the CryEngine 3 to its very limits, offering dreamlike and naturalistic scenes that look plucked right out of Avatar, which wasn't much of a sappy movie compared to the aforementioned Titanic.
It's been in development for a few years now, as its developers had to port it over from CryEngine 2 over to the newer one.