I like to keep track of my games that I have completed, with most of the games it is pretty easy. When the credits roll, I consider them beat, there are a few exceptions of course like Nier, Resident Evil 2 etc. What I struggle with are fighting, racing games and 4x games. I enjoy these genres, but I don’t know what is “satisfactory” amount that would make me think that I played these games to completion.
Some examples:
- Guilty Gear Strive (or any fighting games that are not Mortal Kombat, injustice or SF6)
- Civilization 6
- Project Cars
Just play until you don’t feel like it anymore. If you need a milestone, clear a match/run/whatever on the highest difficulty. Or maybe every variety, so in Civ, a victory of each type. Or if you feel like going hard, find a rating you want to get and get there, like Celestial in Strive. I would say just play until you feel satisfied though. Don’t worry about what others think of your completion metric. None will satisfy everyone.