I consider any game that manages to be fun to be good. A great game exceeds that expectation enough to stand out among the crowd. Beyond that is the realm of classics, which are so notably beyond expectations that they will be 'best list' fodder for decades.

considering U2 is worse than 3 and 4 I have to say TLoU is a great game.

EDIT: by worse I mean not as great cause I freakin love 3 and 4 too much and 3 is the most replayable game I own.  Always a fun revisit

Memorability.... lasting impressions mostly come from great games.
Great games usually have good story, gameplay mechanics ect.

A good game can have a few things that arnt that great, but its still enjoyable to play.

But a few months lateron you have trouble remember names of characters or much of the story... then it likely wasnt a great game.

For me OP I only keep games I really love and can see myself replaying (on easy for a relaxing playthrough after I get the trophies on my initial runs) once a year. Even if I don't get around to it I know they're fun to go back to. I would call all my permanent games that I don't sell away and do this with "great" but that doesn't mean I give them 10/10. Good would be a game I platinum or maybe just play through once then get bored with.

A good game is something that is pretty good, but has some flaws that keep it from greatness.

A great game though is great, exciting and memorable. Something from that game sticks with you.

A good game is a game I play to the end once.
A great game is a game I complete multiple times or explore all content and endings.

Good: Uncharted 4, Great: The last guardian.
Good: The Witcher 3, Great: Fallout 4
Good: Skyrim, Great: Dark souls

A good game is a game that is just well made. A great game usually is game that is not just good, but influential and changes the entire industry.

A good game is talked for a year. A great game is talked for generations.

I dont have examples of good games, but I can tell you Super Metoid is the greatest.

Edit: hmm... TLoU is a good game. Skyrim is a great game. Does that fit my definition?

Opinion

A good game has elements from things that i consider to be great games. I look forward to finishing the game.

A great game is one that I will not want to end. And that when finished every other game I play from that point onward could be tainted as I would expect to see certain things from said great game in every other game I play.

But this could very well be the most subjective topic ever.