The way I'd personally put a numerical value to my thoughts on games would be that my absolute favorite game of all time is the lone 10/10, and all other games are judged based on my enjoyment of my favorite game. It's impossible to empirically rate that, though, so I'd just go by whatever feels right in my gut. So like, Zelda: Breath of the Wild gave me about 85% of the fun I had with Secret of Mana, so therefore I'd give it an 8.5.
This also lets you use all the numbers the journalists never use, so if something is a 3/10, it means I had 30% of the fun with it as I did with Secret of Mana, so it's still worth playing.
If I didn't have any fun at all, it doesn't get rated because it's a 0% and who gives a shit, and that applies to plenty of games, because shitty games don't need granular ratings. Unless you wanna reverse the scale and compare shitty games to the worst game you've ever played.
But that's entirely my way of subjectively rating games on my own opinion. Trying to say which game is objectively the best is practically impossible, because if you run with that sort of concept and break out from video games, you start to try and figure out what's the most enjoyable thing possible, and how one would live essentially a perfect life, which comes down to basically just living in a tank with heroin constantly coursing through your body every single minute from birth 'till death, which is grim as fuck.
