I used to like open world games that would take 50+ hours to beat but I feel like as I get older these games can be intimidating to even start and I often get sidetracked with other games frequently only getting half to three quarters of the way through.
Vanquish took me about six hours to beat and I think that’s what I’m looking for these days. I like games that I can beat in one weekend. Eight hours I think is perfect for me.
It’s led me to playing some GB© and NES games because they often feel a bit more finite.
I don’t think I have a minimum. Little Misfortune and Bright Infinite Memory only took me about three hours to beat but I enjoyed the ride. If a game took under half an hour to beat, like some indie games, I might not be as invested or impacted enough to think about it much afterwards.
Edit: I’m not looking for a definitive answer. Just a ballpark.
Some games like Ultrakill are short and sweet, but others like Factorio can keep you busy for weeks. Both of them felt right for me, but then again I have quite a bit of free time.
If you like shooters, check out anything from New Blood, Turbo Overkill and Postal brain danaged. Those games are segmented into individual levels, which is great for when you just have half an hour.