PC co-op Video Game Recommendations?

Was wondering if anyone could help me pick out a new co-op game for my friend and I to play. Here's what we've played already:

Sanctum 1 & 2 - Enjoyed
Orcs Must Die! 2 - Enjoyed
Borderlands 1 & 2 - Enjoyed
Mass Effect 3 - Enjoyed
Saints Row The Third & IV - Enjoyed
Portal 2 - Enjoyed
Payday 2 - Somewhat enjoyed
Dungeon Defenders - Enjoyable but I found it too grindy
Civilization V - He wasn't a fan - too slow paced
Left 4 Dead 2 - I wasn't a fan
Minecraft - I wasn't a fan
Terraria - He wasn't a fan
Divinity: Original Sin - We both preferred solo to co-op
Torchlight I & II - I preferred solo to co-op, he wasn't a fan

I don't play games with random players, so if it REQUIRES more than 2-person co-op I'm probably not going to play it. Graphics matter to an extent - we probably won't play a sidescroller. We'd prefer an easy way of connecting - via Steam or some other online service.

He's doesn't seem to like strategy games all that much - most of the trap-laying and maze-making in Sanctum and Orcs Must Die! Was done by me.

Ideally:
Fun, challenging combat
Substance (either strategy, story, or complex leveling… Some incentive to keep improving)

Preferred Genres:
RPG
Horror
Strategy (somewhat)
FPS (somewhat)

I'm already considering Baldur's Gate, Icewind Dale, and NWN 2. Dark Souls II has been considered and discarded for now (though we both like the game).

Guest

Castle Crashers and Battleblock theater (both from Benemoth, each one can give you over 50 hours, at least they gave me and my friends).

Orion: Dino Horde (Not that much fun, but oftem this game gets into a 90% promotion, and it is an ok game.)

Forced (Good game, fun combat and very well-made puzzles).

Hammerwatch (Very good game, if you found it too difficult, you can desactivate the perma-death)

Magicka (Hilarious game, the only problem is that even in coop mode, you will find youself trying to kill your friend more than actually finishing a level, so it looses a bit of the coop concept).

Risk of Rain (also really good. You really have to work togueter if you want to survive an significant amount of time).

Tiny brains (really fun to play, great puzzles, the only problem is that it is too short.)

Ok, i could probably say some other ones, but i think that is enough, I would only like to point out is that hammerwatch will need hamachi to work (but considering the games you played, you already knows how to use it), and risk of rain will not work if hamachi or anything, you will need an open port i guess, i'm waiting for the developers to fix that, or at least to say they will, i can't get to play it with my friend… But i played local with my brother and it was really worth it. But anyway, hope this helps, if you have any questions just say it.

Guilherme

League of legends is pretty amazing
i'm not a fan of strategy but its good
or thers call of duty special ops kinda fun
broforce is so much fun its 2 players and can be played on the same pc
OR you can get gta 5, go online, team up and do stuff together
when i fo that with my bros we do TOTAL BADASS stuff
someone answer me please?

hadi

Warframe. Great game. It's pc, ps4, and soon xbox one and it is free. You can choose to do solo or be put in co op with randoms or private match so its just you and your buddy. It is a third person shooter where you can do wall runs you blow stuff up and each character has 4 abilities that can make any losing situation against hundreds of enemies turn in your favor.

Matthew

Resident Evil 6? Never played it Multiplayer, but I've been playing it with a BOT, so I don't really know how it feels. It's a 2-person horror game if you play the Story with someone.
I won't say it's a horror since it's not scary it just gives you the feeling of pressure.

ZeromusFreedom