Immersion to me is the most important quality when it comes to gaming. Various aspects in different combinations can lead to it or break it. It doesn't so much matter if a game doesn't have a deep, original story or innovative gameplay, just so long as the game works collectively.

I don't believe any part of a game is inherently the "most important", but it is important that each part (regardless to how limited) is presented in a manor that doesn't take away from its focus.

Titles like Heavy Rain work because while the gameplay is very simplistic, it does a good job of presenting its core strengths. If the QTEs were clumsy and poorly timed, i'd lose some interest in the story since an unnecessary obstacle had been put in my way. The reverse is often true too, as are many other combinations.

Gameplay is the most important part of any game.

At the end of the day, games are games because the individual(s) ability to interact with the medium.

You mention the end result, which is the feedback that the player receives from the game in question (Whether it be happy, surprised, afraid, disgusted, angry, sad, etc.), but you also mention that what sets games apart from the rest is its interactivity. But interactivity and gameplay are one in the same. Gameplay is described as "the specific way in which players interact with the game".

Without gameplay, there is no game. It is a core foundation on which games are created, and therefore many people see it as one of (if not the most) integral functions that a game should be judged by. A game can exist without a story, or music, and any number of things that we see now-a-days. But a game cannot exist without gameplay. That is why so many people (including myself) prize games on how the player interacts within the game world.

So I'm not necessarily disagreeing with you, but just highlighting why many people prize gameplay over all else.

This is the order:

1.Gamplay
2.Story
3.Music
4.Graphics

Wrong! Gameplay is the most important fact dont forget that videogames are toys

I would love to see people define gameplay, because I imagine those that define it very narrowly won't see it as important as those that define it more broadly.
Is Tetris great because of the gameplay? Or because the challenge of it getting harder and harder? Without the challenge of the difficulty increasing it would get pretty boring. But is increasing difficulty part of gameplay? I'd argue no. But I define gameplay very narrowly and thus make it only one part of many that makes a game good to me or not. Games that have no story need to have some challenge to them or some other way to feel rewarding for interaction with the controls, otherwise they're just boring.

No, in some cases atmosphere can make a game feel fantastic even if its gameplay isn't mind-blowing. BioShock, Assassin's Creed II, The Order: 1886 and Forza Horizon 2 all prove this, atleast to me.

You make some good points, but it will largely go unnoticed by fanboys who are hellbent on putting certain game down even though they've not played it.

Indeed. Good graphics always make me feel nice and fuzzy. There are certain games and genres where I don't give a fuck about gameplay because I just want to experience it.

TLOU is a good example for this.