Looking for a Good Co-op game.

[Honest Tiefling]

For an older games that I can recommend, there's Titan Quest, which is Diablo II, but Greek monsters instead of Abrahamic. Got an upgrade with the Anniversary edition a little ways back, and the existing community is pretty good.

Going to second this, Titan Quest is quite good. I think Grim Dawn is better as it is essentially an updated version, but Grim Dawn is...Grim. Very Grim.

Titan Quest is quite fun! The only balance issues I can think of is that the Nature and Dream masteries seemed strong, but not so strong you couldn't just carefully pick different masteries to keep both players competitively, such as only having one person do Nature.

I'll also mention Killing Floor (1 and 2) as good zombie shooting fun, though it does get repetitive if you do too much in one sitting.

I'm going to disagree with you here. Killing Floor 1 was very fun, but when I played most of the dialog was the male characters screaming about how completely and utterly not gay, nope, nope, nope, no homo for this guy, no sirree bob they were TOTALLY NOT GAY while badly voice acted female kept trying to hit on these idiots concerned with their sexuality in a zombie apocalypse caused by a guy in jorts. If you do like the game, either don't play a healer or get the DLC to get better dialog.