Despite mechanics such as drop-in and drop-out co-op becoming more common, like in recent games such as Far Cry 4 and Assassin’s Creed Unity, Doom won’t feature such mechanic. The lack of campaign co-op was confirmed by Marty Stratton, Executive Producer of Doom, at QuakeCon on Saturday. For co-op experiences, gamers will have to stick to Doom maps created in SnapMap.
Stratton also said you can create custom single-player campaigns using SnapMap:
In a sense. You create a level experience, and then to create a campaign-type thing you would link those [levels] together in, like, a playlist.
You wouldn’t necessarily carry weapons from one level to the next,The author could set it up knowing you have this set of weapons as you go into this next component. It’s little bit more like a playlist.
Stratton also said that co-op support is “something they will think about in future iterations”. Although most Doom fans don’t seem to mind, after all most of them are used to not having co-op support when playing the Doom campaigns, besides, in PC with mod support, it could be added, let’s not forget the great things the modding community has achieved on most games.