You think they won't use pre-rendered stills
that's so fukking adorable. W3 still used skyboxing, pre-rendered stills, and five year old parallax mapping. Bruh, do some research on game developing. Just to help you out, there is not one game out currently that has full 3D rendering, that kind of game would be a fukking movie, about 200+ gigs, and would run on two beefy pc's. A Pixar film is entirely 3D, everything has to have a "filling", models have to be able to bounce, warp, touch, etc without clipping. This is a process that takes not that much time, but a shyt-ton of workers and money. And even then its not rendering real time, its a recording...hence why they're so small, but even then, its about an hour or so....games are obviously longer.