I also reccomend deep rock galactic, the devs are very involved in the community. The community is (mostly) amazing. There isn't much story and it is completely hidden in the in game encyclopedia and the wiki. No drm (apart from steam) and lots of content and depth that keeps you hooked once you make it to your first promotion.

If you want no DRM, you are basically only going to get your games from GOG.

https://www.gog.com/en/games?tags=fps&features=coop&order=desc%3Abestselling&hideDLCs=true&releaseDateRange=2015%2C2025

Halo is my top pick, the first three have great stories and couch co-op if you need that, and if you get the master chief collection (halo mcc), the multiplayer is great and you can find tons of forge mode maps created by people, from race modes to mini golf haha

Gears of war is also fantastic, epic story, fun gameplay, and who doesn't love a chainsaw bayonet lol

Deep rock galactic is another really fun one, I can't say there's too deep of a story too it, but it's endlessly repayable with all the combinations of weapons and procedurally generated missions.

Helldivers 2 is fantastic fun and I still play it weekly, even though I'm max level with everything unlocked.

Halo 1, 2, 3 & Reach

Does portal 2 coop count? Technically it's a FPS

Left 4 Dead 2 has a split-screen mod.

Remnant 2, it's third person but it's one of my favorite games ever.

Borderlands Borderlands 2

• all the DLC's.

Then if you're still interested, Borderlands Pre-sequel

And if you find yourself really into the series, Borderlands 3

Halo 1 and 2

If you know how to sail the high seas and emulate things, Halo coop is easily my fave.

TimeSplitters 2 and 3 were pretty great

Killing Floor.

What do you mean by DRM here? Are you saying you need to be able to pirate it?

I've had a lot of fun with Roboquest.

Sanctum 1 & 2 are fun fps mixed with tower defence.

Deep Rock Galactic is fantastic, like others have mentioned.

When I was a kid I had a blast playing Time Splitters: Future Perfect on my friend’s PS2. Such a fun game, with a great co-op story mode.

• Shadow Warrior 2 (avalaible on GOG)
• Half-Life 2 has a mod for campaign coop (Synergy if I recall correctly)
• Lots of zombie games : Left4dead 2, Killing Floor 2, ...
• Borderlands

First Person but not totally shooter :

• Dying Light / Dead Island
• Vermintide / Darktide

Borderlands series (Tiny Tina's Wonderlands as well), Gunfire Reborn, Vermintide 2, Helldivers 2, Remnant: From the Ashes, Valheim (not fps but you can use mods for first person view) and coop is amazing in Valheim, Nioh 2. Also could do Gears series (3rd is best, 4th and 5th are ok but still decent fun with friends).

I've been into co-op games lately with my friends.

Edit: steam spring sales is coming soon™. Can't wait to grab a few of those.

Seconding Dying Light 1 and Borderlands 2. Excellent games! If you're open to 3rd person, Helldivers 2 and The Division 2. No idea about DRM, though.

A Way Out is an interesting one. Very story driven with some FPS stuff near the end.

Suggestions for local couch coop anyone?

Serious Sam! Silly epic arcadey coop fun.

Just got Robocop and Wolfenstein New Order on a decent sale on GOG, loving Wolfenstein so far..

Love Left 4 Dead 2, timeless classic.

Call of Duty 3, World at War, Black Ops 1, Modern Warfare 3, and Black Ops 3 all have local split screen Co-op as an option