Name any 'AAA' shooter in the last 2-3 years with a 15 hour single player.
Longest one I can think of is wolfenstein new order which I have 12 hours played, and I'm 2/3rds of the way through my second playthrough.
My stealth playthrough of metro last light is on 15 hours, including a restart.
Depends on how you play the game

I take my time and explore every single corner of a level/game.




A conquest type mode is super basic and should be a bare minimum to be honest. I really hate the heavy online bias in games now.