One of the best co-op games, and one of oh-so-few stealth co-op joints around, Styx: Shards of Darkness, is 85% off (just $2.99) for another couple days. With the Steam Summer Sale not quite closed, it's not too late to toss some pocket change at another couple games. Better yet, talk a friend into playing with you.
I routinely cycle back through my whingeing that co-op campaigns just don't exist like they used to and Styx: Shard of Darkness was the answer to my grievances when I picked it up a couple years back. It's a proper stealth romp with large levels to dissect by picking off guards and avoiding combat with darkness and crawl spaces. All you've got to suffer for it are some bottom-shelf scatological jokes from a snarky goblin.
