I have 2 iPods 5.5G 30GB and iPod 5.5G 80GB. I installed Rockbox 3.15 on all of them. Wolf 3D works OK on my 80GB iPod but doesn't work on both 30GB iPods:
Can't open /.rockbox/rocks/games/wolf3d.ovl
This file exists and is idenctical to the one on 80GB iPod. The same situation with Duke Nukem 3D.