I had to put this game down after a few hours as no matter which video settings i tried even the very lowest I couldn't get the game to stop giving me a horrific headache. Never had that problem before. I have an hd 5800 series gpu. Is that just never gonna work for this game at a level that doesn't destroy my eyes/head? I know the card is getting older but I haven't had any problems running anything with the card up until now. I've certainly never experienced a game giving me a horrible headache....far cry 3 was fine.
Just a recommendation, but have you tried increasing the FoV? That could have something to do with it. I have been playing on my TV and have the game at a TV appropriate FoV. I was sitting at my computer desk playing a bit and the low FoV was getting me feeling sort of weird. Kind of nauseous.
If framerate is the issue then perhaps try going into the advanced video settings section and set VSync mode to sparse. It should lock it to 1/2 your refresh rate, which will likely offer a stable 30fps if you're willing to make that compromise. If not, then as a heads up you can get a small FPS boost if you go into your Far Cry 4 GFX config file and disable ATOC.
Also, I would still recommend checking out the Nvidia performance guide for the game, because it gives a relatively good idea of what kind of impact each setting will have on your framerate.
http://www.geforce.com/whats-new/guides/far-cry-4-graphics-performance-and-tweaking-guide
So...I'm watching Vinny from Giant Bomb play FC4...
https://www.youtube.com/watch?v=JhyoW38CDdk
Is the game always this buggy? It's like, buggy for 3 straight hours.
I had the game crash on me twice during the intro, but after that I've sunk a solid 6-7 hours in without anything major happening.
Apparently most of what's happening (except for that offline mode not working stuff, that was total shit) was due to a bug from using a DS4. If you use a DS4 with the game apparently it can possible break scripting and cause all the fun bugs you saw.
I've been playing with a 360 pad and it's been mostly fine.