Doom (2016)

John Carmack confirmed in August 2007 that Doom 4 was in the future plans of id Software. On May 7th, 2008, id announced that the development of Doom 4 had begun.

Speculation
The game is most likely to be based on id Software's upcoming id Tech 5 game engine. It is also possible that Doom 4 will be a remake of Doom II, or will otherwise be set on Earth. Todd Hollenshead, the CEO of id, has made a statement which arguably supports this speculation. The comment was as follows: "Doom is part of the id Software DNA and demands the greatest talent and brightest minds in the industry to bring the next installment of our flagship franchise to Earth".

Doom 4 might bring back built in coop. Doom 1 and Doom 2 had built in coop but Doom 3 REMOVED built in coop and is only available with an user made mod.