[Kyrio]

Not to mention most of those use ILM Stagecraft which, despite being Unreal-based in its first version, has been using a custom engine for some time now.

[ryanlitalien]

Do you have source? From what I heard last, they're using a heavily modified version of Unreal.

[pfranz]

Here's a HN thread asking the same question: https://news.ycombinator.com/item?id=29169143

Anecdotally, I've heard the same thing. Lots of articles will say things like, "ILM increased the resolution of StageCraft with its in-house renderer, Helios" but never explicitly say they dropped Unreal or exactly what changed.

[bhouston]

I heard as well that they moved away to custom software.