>>44
Uhh... Rage's not taxing at all on the graphics side. The technology works by reading a unique texture foe everything in the world. Since each texel is unique, it comes pre-shaded and pre-lit.
The advantage is that it can look as good as you want and it'll be cheap on the hardware. The disadvantage is that it's completely static, you can't even move lights so the shadows move around.
The trick is loading the right textures at the right mipmap levels at the right time. And also storing the huge amount of data on disk (this is the biggest problem I see for an iPhone app). But the rendering itself is pretty simple. It does use pixel shaders, but only to ease the transition between several texture tiles at different qualities and stuff like that.