Hidden attributes

If these hidden attributes have any linear or 1:1 visual representation, then this does not count since you already can see it.

Reasons for hiding this information can be any number of things, first and foremost comes immersion because it's something you wouldn't know for yourself either, another is to make metagaming harder and make the player more reckless (or careful if they understand it) because they have no direct way of telling how much more they can do something before they're punished for it (e.g. karma), possibly (though unlikely) an oversight from developers, etc.