A model of immersion

[kyoryu]

I think there is one interesting idea - is the decision-making based upon information available to the players, or the characters, in a pure sense?

Daily abilities are. For whatever the reason, they're abilities that can be used "actually" once per day. A person in the world could test this, even if it's ludicrously precise. The information needed to make the decision (do I have the ability? Is it a once per day ability? Have I used it today?) is all available to the character.

OTOH, per-session abilities are not. Nor are things like some levels of GURPS Luck that are based on clock time. An ability based on seating position at the table would not be, either. Generally, luck/meta abilities are not - Savage Worlds bennies, for instance, are explicitly granted for non-game related things (making the GM laugh, for instance).

This is a fairly rigorous and objective definition - it also explicitly doesn't get into how realistic something is - just whether or not it relies upon information from outside the "model" of the game.