Primarily a single-player game, DOOM Eternal doesn’t skimp on its campaign.
Upon starting DOOM Eternal for the first time, you’ll have to select a difficulty level. Providing you choose one that matches your skill level, your first playthrough is likely to take around 15-20 hours, depending on how thorough you are.
You see, the majority of DOOM Eternal‘s levels have many collectables for you to find, as well as secret encounters and Slayer Gates. Run through the game without finding/picking any of them up and you won’t be able to upgrade the Doom Slayer very much. Therefore, it’s a good idea to use the game’s new fast travel feature and sweep up collectables where you can.
Once you’ve completed DOOM Eternal you can return to any level via mission select, and even enable a wide number of cheats. There are also Master Levels for you to beat, which will be released periodically, and a weekly challenge and levelling system provides plenty of cosmetic goodies to unlock. Throw on top the multiplayer Battlemode, and you have a game that you could be playing for 50 hours plus.
So, it takes about 15-20 hours to beat DOOM Eternal‘s campaign, but if you want to get all of the game’s achievements/trophies and engage in its multiplayer, you could find yourself spending twice or even three times that amount playing.