During the Bethesda E3 press conference id Software revealed what they have planed for Doom in the near future.
All minor updates to SnapMap and multiplayer will be free. The first batch comes next month a will include three new modes; free-for-all deathmatch, Exodus and Sector.
The studio also announced that a paid multiplayer DLC is on its way. It's called Unto the Evil and will feature three new maps (Cataclysm, Offering, and Ritual). A brand new demonic enemy called the Harvester will be introduced as well. We'll also get to play around with our character build, as new guns, armour and taunts are introduced.