From my experience in games/simulators, here is the best coop games and sims (Alphabetic order):

- 112 Notruf 2
- 7 Days to Die
- Arma 3
- Barotrauma
- Bus Simulator 21
- Carrier Command 2
- Chivalry 2
- Deep Rock Galactic
- Don’t Starve Togheter
- Door Kickers
- Escape from Tarkov
- Escapists 2
- Falcon 4
- Farming Simulator 22
- Firefighting Squad
- Generation Zero
- Ground Branch
- Guns of Icarus Alliance
- Hell Let Loose
- Hunt Showdown
- Il-2 BOM/BOS/BOK
- Insurgency Sandstorm
- Keep Talking and Nobody Explode
- MechWarrior 5 Mercenaries
- Minecraft
- Mordhau
- Mother Russia Bleeds
- Overcooked
- Overcooked 2
- Police Stories
- Precision Simulator X
- Pulsar: Lost Colony
- Rainbow Six Siege
- Ready Or Not
- River City Ransom Underground
- SimRail
- Six Days in Fallujah
- Space Hulk Deathwing
- Snowrunner
- State of Decay 2
- Steel Beasts Pro PE
- Storage Inc 2
- Stormworks Build and Rescue
- Swat 4 Gold
- theHunter Call of Wild
- Wolfpack
- X-Plane 11 (with Smartcopilot add-on)
- Zero Hour

If you would like to have fun in coop playing with some of them or want to know more about each one, catch me on steam ;)