I feel like there’s a very big tonal difference between Episode 1: Knee-deep in the Dead and Episode 2: The Shores of Hell.
I usually wouldn’t use the term ‘lighthearted’ to describe DOOM, but compared to the dark and foreboding atmosphere of Episode 2, Episode 1 feels almost ‘lighthearted’. I think this tonal difference is reflected in the soundtrack, too. We have the classic At Doom’s Gate, a very energetic theme ripped straight from Metallica’s No Remorse, and it makes the perfect backdrop for high-action demon killing. Sinister is quite the opposite, it’s suspenseful, subdued, and coupled with the visuals of it’s respective level; can make you thoroughly uncomfortable.