1. Burn or mount the .iso file
2. Run the setup and install the game, the physX and the Directx
3. Go to the .iso in \Darkest of Days\setup and install oalinst.exe(open AL)
4. Take the crack in SKIDROW folder in the .iso and place in the game folder
5. Enjoy this great game
if don't know this game...
take a look