I don't think the "out of 10" or "out of 5" stars or ABCDF or "out of 100" systems are that useful these days.

Price is most important I think. Is the game worth the price? That's all that matters.

Here's how I value the games I've recently played

Gold Rush Anniversary: $1
Ys Origin $10
Albion Online: $1
Game of Thrones - A Telltale Game Series $10
The Lord of the Rings: War in the North: $4
Undertale: $2
Broken Sword 5: $10
Civilization VI: $10
Cities in Motion 2: 25 cents
Tropico 3: $10
Civilization 3: $10
Mirage Arcane Warfare: $3
Trails in the Sky (#1): $4
Enslaved Odyssey to the West $3
Skyrim $10
Realms of Arkania Blade of Destiny Gold Edition $1

OK some of the 10 dollar games may actually be worth a bit more than 10 dollars but I won't differentiate atm. I'm cheapo after all.

Well on Gordon Ramsay's cooking competitions either Hell's Kitchen or MasterChef they frequently have that individual competition where he invites guest judges to judge based on what they would pay to what was served to them.

You're right though richer people would probably rate games higher value-wise. But most games fall under the $100 range. then we're just going back to the 1 to 100 thing then kind of ... eh ... it feels like it'll just be a "Value" Rating.

Games are a time investment as much as they are a monetary one. We can play countless games for free, but most of the time you wouldn't bother.

Alternately, some games are worth any price. But there's no way to know the trash from the treasure so we often end up paying very little either way.