It's critical that the controls be usable and responsive. Graphics aren't so important, as long as they're viewable. You can think of graphics as being comprised of two parts - (a) quality and (b) style. The latter includes, for example, whether the game is designed to look realistic or cartoonish. I'm tempted into realism, but just as over-saturated colours aren't realistic, neither are
under-saturated colours. But good luck getting it right in a world in which modern displays are usually over-saturated on purpose

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As for the plot...it's nice if it isn't the same old story for every game in the series.