11th January 2017, 9:20 PM
From what I've hard DOOM (4) actually started development as a CoD-like game, and that version got pretty far into development... when they decided to can it and start over with a new idea for a more classically-styled shooter, which is what you see in the final game. So yeah, they did have a good focal theme, but it changed mid-development. They stayed focused otherwise with each version though, so the game did eventually get finished.