I think I've seen "questions" like this on stackoverflow but sorry if I'm overstepping any bounds.

Inspired by my recent question and all the nice answers (Checklist for finished game?) I think every gamedev out there has something he/she thinks that almost every game should have. That knowledge is welcome here!

So this is probably going to be an inspirational subjective list of some sorts and the point is that anyone reading this question will see a point or two that they've overlooked in their own development and might benefit from adding.

I think a good example might be: "some sort of manual or help section. Of course it should be proportional to how advanced the game is. Some users won't need it and won't go looking for it but the other ones that do will become very frustrated if they can't remember how to do something specific that should be in the manual".

A bad example might be "good gameplay". Of course every game benefits from this but the answer is not very helpful.