High frame rate, stability, good quality animations, color palette/art style/fonts that are consistent with the game fiction, UI usability, soundtrack, community, abscence of cheaters... just to name a few.
You can have a great game, but if it's unstable, has annoying sound effects, or constant monetization related nagging, or a toxic community or some cringy voice actor or soundtrack or excessive unskippable cutscenes with irrelevant stupid dialogs... the magic in the experience goes away. Everything counts.
If you go to a 5 star hotel where everything is perfect but when you try to use the shower it doesn't work, your overall rating will be 1 star. For a experience to be gratifying, everything needs to work together.
I've read countless articles and postmortems of the style "why X is successful", and then seen games that follow those documents closely and produce a horrible game. Because they are unable to capture the whole experience.
Lately I played a game, Ex-Zodiac, which is a StarFox clone. Only the demo is available, but the author really captured every single aspect that made StarFox great. That attention to detail is what makes games fun.