Melee combat.
Just kidding.
I have an easier time to play a game, if it conforms to established control schemes. But each decision you make, will define your game. What is needed in one game, might be distracting in another.
I assume you talk about game features and not meta features. Reassigning controls would be a meta feature. So would a color blind mode or having a center dot being displayed.
So, no, I can't think of must have game features, but a lot of meta features that one can summarize under QOL.