Copy diabdat.mpq from your CD (or GoG install folder) to:
~/.local/share/diasurgical/diabdat.mpq

Game saves and diablo.ini are located at:
~/.local/share/diasurgical/devilution

~ is your home directory, /home/retrofw by default.

Controls:
- D-pad: move hero
- A: attack nearby enemies, talk to townspeople and merchants, pickup/place items in the inventory, OK while in main menu
- B: select spell, back while in menus
- X: pickup items, open nearby chests and doors, use item in the inventory
- Y: cast spell, delete character while in main menu
- R1: use mana potion from belt
- L1: use health item from belt
- Start + Up: game menu
- Start + Left: character info
- Start + Right: inventory
- Start + Down: map
- Start + Y: Quest log
- Start + B: Spell book
- Select + A/B/X/Y: hot spell
- Select + D-pad: move map/cursor
- Select + L1: left mouse click
- Select + R1: right mouse click
- Start + Select: game menu
- Suspend: map
