Is it a full game? I've read it's a quasi-sequel to FC5, but not sure if it's DLC or self contained game.

It's a full game, actually quite different from FC5. I got about 1/3 of the way through it a while ago and plan to finish it some time, whenever my FC5 monomania wears off. If you like freaky, trippy stuff like Manthorp ...

I'm not a fan of the trippy boss battles in FC4, but the trippy Reggie and Yogi missions were a big highlight. If there's more of that sort of thing, then it's definitely gonna be worth a look. 

I've got a small collection of large RPGs to get through in my Steam library that I want to look at after I finish FC5. They've been lingering around for quite a while. I started Skyrim waaaay back, but got far too distracted with side quests and was 50 hours in before I saw my first dragon. If I start playing that again I'm likely to never need another game. 

That said I've started looking at the free F1 game (2018?!) you posted about the other week, there's a surprising amount to it, an in depth career mode which, depending on the team you choose, gives you a set level of expectation that's not necessarily about winning. 

One thing I can definitely recommend for FC4 is the Yeti DLC.

C'est moi...

I kind of liked the shroomy stuff in FC3. It reminded me of a) actual shrooms and b) some wonderful passages in Robert Stones' Dog Soldiers.

I also liked the shootout in the hallucinogen factory in FC4, all to the sound of Panjabi MC.

Yeah. I prefer drug-induced over digital, but whatever.

With the notable exception of the now deceased, Dead Island and L4D franchises, I have always been disappointed by zombie-themed FPS. I took a run at Dying Light (DI's supposed successor), and may return to it in future. Its zombies are dangerous, but not scary and loathsome. The parkour thing is sort of fun until it turns into a puzzle-solving thing which is often. I played through Wolfenstein TOB, and while its set-designs were fantastic, the creatures were meh, and the zombies even moar meh (I got TNO as a twofer deal, haven't installed it. Maybe I will, maybe I won't).

Last night I drunk-bought Dead Living Zombies (DLC for FC5) for the princely sum of $Can. 3 and spun it up for a minute of gameplay before retiring. It appears to be be, more or less, worth the price of admission -- I'm seeing retread concepts stolen from L4D and TOB both (alas, none from DI). One original thing is the comical graphic novel storyline about a scriptwriter pitching these preposterous scenarios to skeptical studio heads. So that at least is different. I love trashy and stupid graphic novels, so long as they deliver on graphics and outre storylines.