I don't work in 3D graphics but it seems challenging to me because of the fluid dynamics. Fire is very low density gas rushing upward into the moderate density

I don't work in 3D graphics but it seems challenging to me because of the fluid dynamics. Fire is very low density gas rushing upward into the moderate density air - and even if you can do all the fluid dynamic calculations to render the boundary of the flame, you also have to render the light it's throwing onto the surrounding surfaces. I have no idea how close technology can come at this moment but I'm not surprised the answer is "not close enough for prime time".