Is that game any fun for a single player, or do you have to play with others?
I want to straight up tell you "No", especially after having loads of fun with this game in multiplayer, but it's definitely geared towards a multiplayer experience, similar to The Division. However it's best enjoyed amongst like minded friends who got patience, 'cause you can't just go guns blazing, thinking you a 4 man army, you will get fukked up and that's the case alot of times when playing with dudes who want to run and gun 'cause instead of hitting objectives tactically, they just wanna charge the gate and fire, which leaves you dead 4.5/5 times.
With that being said, if you play with a tactical squad of friends, (Microphones very important) and y'all on the same page, marking targets, taking fools down in stealth, doing synchronized sniper shots (You've the ingenious option to mark up to 3 or 4 targets with numbers so you can choose who takes out who or whatever) gathering intel/weapon caches etc.....after doing all of THAT, playing by yourself is not only boring in a sense, it's a bit of a chore since you got to manage the 3 AI guys and that poses a problem for some people (Myself included) during fire fights or just in general since a human player would be able move by theyself as opposed to you having to set waypoints and do all that micromanagement shyt while getting dumped on from each corner.
Playing by yourself (pause), is vital for collecting weapon caches (New weapons) Weapon kits (Weapon attachments) and all the other intel marked on the map that your friends might not be inclined to help you get, so I see playing singular as a way for me to level up my skills and I use multiplayer to attack missions that I'd prolly die on myself.
Singeplayer is cool, but all the fun is with rolling/fighting with a squad 'cause your team AI, while competent can't replace human interaction in doing covert shyt or trying to survive a firefight.