Omori is the most depressing game in existence. It would be seriousy hard to beat that. If there is a more depressing game than that one I would like to know it.
Diablo 3 definitely works. Path of Exile can work wonderfully as well, though not as well as Diablo 3... If you ignore the build aspect in it and just pick up and use what seems fun. Do not make proper builds in Path of Exile, your brain will explode... And do NOT read into the story. It requires a bloody detective to piece it together.
Another thing is... Any borderlands game on low difficulty is quite relaxing and fun. You will not have to think too much and just enjoy the adventure, action and loot. If you explore and do alot of sidequests you will find the experience most satisfactory.
This. Fuck yeah. (I don't have Powerwash Simulator but I heard it's really calming.)Vampire Survivors or simulator games like Powerwash Simulator
I noticed that playing on handheld (phone or Switch) also helped me as it's less effort compared to PC.