What are the most important factors for developing a game?

Question

I would like to know this in order to understand why some games like Mario are still playing today, but because there is no other. This will be implemented in future gaming projects.

What are the most important factors for developing a game?

Gameplay or graphics? Both?

EDIT:

Is it possible to combine these two?

Answer 1

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Answer 2

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Answer 9

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Graphics can be a nice addition, but just because the game looks beautiful does not mean that I will spend hundreds of hours on it. The Titan Quest would be a good example of taking the Diablo II style and adding some candies that make a fun game.

Nostalgia is a big factor in why some old games still play like old Super Mario games. Memories of how to play these old games and see how great it was to get to the next level might be why some will come back again and again. It is for this reason that I still occasionally play SNES.