Not to muddy the water but there's also cataclysm: bright nights & cataclysm: the last generation as alternative forks as cataclysm is an open projects & c:dda devs are known for... interesting choices & attitudes so its good to look around at the forks to which variant is more for you!

Also they're all free from their github pages, I really would not recommend if you do go for cdda, buying it on steam.