There Are Loads Of Collectibles
We all fondly remember that Doom 2016 had fun little easter eggs and toys that were nods to the original Doom games and Quake. Doom Eternal takes it to a whole different level by adding a whole bunch more extras. Instead of just various Doomguy figurines, the game adds toys of every different enemy and character you can think of.
Additionally, records of songs from different Doom games, posters of bands and people, and plenty of lore texts can be found throughout the levels you play through. To add to all of that, fun little cheat codes that give you perks like unlimited ammo can be collected for use within the levels.
Getting 100% of the collectibles in the entire game will be a feat all on its own but it will definitely be fun to see all of the nostalgic items and tools the developers decided to put in the game.