Hmm, which texture do you have in mind? The tortured terrain on the "land" area? That's done with a plain white layer in PS set to emboss blending options and then carved and chiselled with a layer mask. I used different brushes, from plain round to some texture, dry media and others. Another option would be to just set the whole layer mask to 50% grey first, then lower terrain with darker brushes and raise it with lighter ones.

The black "limbo" areas are one layer higher up, basically just a b/w layer set to multiply and painted with variable opacity round brushes.

As for the grunge - it's a sepia tone hue adjustment layer, a grunge border layer manipulated for more sharpness and on top a dusty screen layer.