Keanu Reeves.
Jokes aside:
- A great game has to have good quality of live features (QoL), to avoid frustration. QoL does not have to be stellar, but it needs to satisfy some minimum requirements. Depending on the type of game, those may be, for example:
*easy inventory management
*intuitive controls for characters
*if there's lots of backtracking: fast travel
*if turn based combat: faster animations or skippable animations (as options)
- Lore, worldbuilding should make the player curious. The world should be consistent.
- Characters should have some depth and, ideally, a believable development process they go through over the game.
- Story-telling should be great. That does not necessarily mean walls-of-text or unending dialogs. A great game can further the story even without using written or spoken language.
- This includes very good pacing. Obviously, it should not be too short. But don't draw out the story too much either, or people burn out before they reach the end.
- Graphics should fit the game and the budget. High-fidelity 3D graphics are nice, but they can also look fairly generic if you don't invest some sort of man power. I prefer well-done 2D graphics (or even pixel-art) to poor 3D.
Of course there are many more issues to consider. This question is pretty difficult to answer in general, because there's so many individual things that need to be just right. The points above are just the first ones that came to my mind.
IMO the world/setting doesn't matter.
The most boring world can feature the most exciting game just like the superb world can produce a game of boredom and frustration.
I agree with the latter (good world/setting, boring game). Plenty of examples for that. But this does not make world-building irrelevant. Specifically, I do not think that you can have a great game with a boring world/setting. At least I can't come up with an example, unless you start straying beyond RPGs.
There certainly are RPGs that are (intentionally) vague when it comes to lore/world/setting. That, in my opinion, is not the same as boring or poor. If the developers are good at what they are doing, a setting where the player does not know alot about the world he "inhabits" is one that can be extremely interesting.