Pretty nice work there. I'm going to guess that a lot of it was done manually in general purpose tools like Maya. Some of the vine growth and other things might have been done semi-procedurally, with Houdini or some other very flexible tool. XFrog or another system (Xfrog seems most likely to me just based on the types of plants) may well have been used as the basis for some of the plant models, too.
- Oshyan