While I agree that Diablo 2 was a huge game content wise, It was totally done in 2d.
The only real 3d options were when you set it to do "perspective" and this really only stitched together 2d tiles onto a 3d plane to give it a more 3d feel. There was also some hardware lighting, but that could be done without on a ppc.
Everything in the game was prerendered sprites. I started work on a diablo 2 esque landscape program which runs just fine. Just like most of my projects though, I barely have time to code with this being my last 2 semesters in collage.
A diablo 2 type game could totally be made for the pocket pc, of course, it would need to be tailored to the specific memory requirements. The largest part of creating a game like this would be the content generation. The coding is almost the easy part compared to how many monsters/sprites you would need to come up with.
