9. Equip Better Armour Sets In Multiplayer
I'm including this as initially I was pretty disappointed with the very basic armour sets available in the multiplayer. However, after seeing other players marauding around as angular demons and pointy-armoured evil lords - and after hours of levelling up and unlocking such parts I couldn't seem to equip - I went back into the customisation options for another look.
Now, it seems I'm not the only person who missed this if the abundance of posts online are anything to go by, but once you're inside the 'Customise Armour' menu, look to the tiny font underneath which part you're swapping out, and you can actually hop left and right into different categories.
Outside the Master Chief-like 'UAC' set are a host of more demonic, hellish options, which are WAY more in-keeping with the heavy metal aesthetic DOOM is going for.
As I've said, this might be obvious to some players, but for whatever reason (mostly the tiny font) it's passed many of us by, too.