Take a look at the Sniper Elite series. It's third-person and plays a lot slower than a COD game, but it is full co-op and takes place in WW2. The newer entries also look pretty nice.
Thanks, we tried this earlier but me and my buddies can't seem to do stealth no matter how much we try.
Now if it can be a viable strategy to go guns blazing then that'd be a different story.
I got the impression they won't like either of those based on the post. Which is a shame because they're great. You can spend a night with a couple friends going through pretty much any of the Halo games, and with the Master Chief Collection you can turn on skulls and such and have access to all the great Halos in one.
Yeah, not what we're looking for right now but we've played through halo games and it was a blast. GOW didn't sit right with us, perhaps due to the third person view, but we are going to give it an another try in the future. Just now, we got the COD itch. We've completed world at war campaigns so many times that now we just blaze through it on full autopilot now...
Does it have to specifically be semi-realistic, have old guns, be military themed and in first person? Cuz I know some fine twin-stick sci-fi co-op shooters that can fill the same "shoot everything that moves with minimal effort" itch but they aren't realistic, military themed or first person.
Like Synthetic 1 and 2 or The Ascent. I know of a couple WW2 games also similar but they completely lack co-op (or any kind of multiplayer for that matter) except for Jagged Alliance. And those games are old (except for the F2P thing that might not even be around anymore).
You could play Ghost Recon: Wildlands or try some of the older Ghost Recon or Delta force games. Some of the weapons on offer are older in it.
There's a tag on Steam named coop campaign that might help find a few for you. I saw a real time tactics game called War Mongrels that might be of interest though it's obviously not a shooter.
Also, obviously there's "hell let loose" but it's not a campaign experience