I'm sure most people with any interest in the genre have probably gotten around to playing Doom. It's one of the best FPS games around, and I'm speaking as a huge fan of the original games. In a bit of a surprise move, Bethesda recently announced that current Doom DLC will no longer be behind a season pass, available to anyone who purchases the base game. And now if you own a PS4 and still haven't had a chance to try it out, you can play Doom for free this weekend.
Of course this will require you are a Playstation Plus member, also a necessity if you want to enjoy the online multiplayer modes it has to offer. Multiplayer in Doom started out kind of shitty, but quickly improved as new updates were released. I still think SnapMap was a bit of a letdown, but find myself playing the various Deathmatch modes from time to time. It's good simple fun.
[Clarification: A user pointed out, to be specific, that the multiplayer is unlocked in its entirety this weekend, but the single-player is restricted to a two level trial. Bummer!]