Best PC single player FPS?

[Salty22]

Got a new acer x34 monitor and new mouse so really craving playing a new FPS but im totally crap at playing online, so would really like something single player.
What would you guys suggest?
I got Doom a few months ago and been enjoying that but fancy a change.

 

[Salty22]

Read the title and thought of Doom immediately but it seems you have that covered in the OP
Another vote for Borderlands 2, although it can look quite dated now.
FEAR is very old now but it has timeless gameplay.
Stalker is basically the Citizen Kane of PC shooters but it's a product of its time as well and can take some getting used to.

Finished FEAR on the xbox 360 years ago, loved it.
Actually have Borderlands 2 but not played it, might have a go