Optional VS AI Co-op: Team up and defeat different bosses on this board/card game. Dozens of different characters to pick from and over a hundred cards for your deck. Fun, casual, and relaxing.

Full co-op: An entertaining game with enough prestige (insanity) levels to keep you going for a while. It can get considerably grindy if you plan on reaching the highest difficulty.

Full co-op: Pretty graphics, strange mix of tactical gameplay with bullet-spongey enemies. Customizable gear. Gets quite grindy and some of the best gear is locked behind PvPvE areas.

Full co-op: Tower Defense mixed wth FPS mechanics. Quite enjoyable and doesn't require any grinding for gear, but it only features 16 missions, so I'd recommend getting it on sale.

NOT STRICTLY CO-OP: You may team up with your friends to hunt different animals in this beautiful game. The downside is that only one person will get the rewards. Requires lots of patience.

Limited Co-op: The co-op mode consists of a linear set of fights which pales in comparison to what the single player campaign has to offer. It also forces a rather bad gear upgrade system.

NOT STRICTLY CO-OP: 4X game set in space where much like in Crusader Kings II you can ally with your friends to play against the AI, or simply to roleplay your galactic empires.

Full Co-op: A small humorous physics-based puzzle game with different ways to complete the goals. Features some easter eggs and secrets that add to its replayability.

Full co-op: Greately addictive and fun sandbox with a focus on exploring, building, and crafting. Tons of available content to satisfy everyone's needs. It can be a bit grindy at times.

Full campaign co-op: As interesting as this game may seem, the netcode is trash; there are reports from 2013 about the lag making it unplayable. They weren't fixed by late 2017. Can't recommend