On Game Design - Game Design Theory - page 31

We should be just as concerned about elegance when it comes to input
resolution as we are when it comes to adding new features or mecha-
nisms to our systems.
Feedback
Feedback is the term used for the opposite of input— output . It's how
the game responds when you put information inside of it. In all games,
this means feeding the input into the ruleset and outputting the result.
In chess, if your input was “move to D4,� the rules would require you to
check to see if there was already another piece there. If there is and it's
yours, the move is illegal. If there is and it's your opponent's piece, the
piece is captured. Either outcome is feedback.
In video games, feedback is often a way to refer to the visual or au-
dio representation of the actual feedback. The number 100 flying out of
Mario's head is the visual feedback that shows players what the system
fed back to them for their input: 100 points. It's important to know the
difference between actual system feedback, and how a game visually or
audibly represents it.
Execution versus Decisions
Some people believe that an execution barrier is a kind of decision, and
that systems such as Guitar Hero are games because they include these
barriers. I think that this is a very strange way to use the English lan-
guage. If you're walking across a room and you trip on something and
fall, and someone tells you that tripping was a “bad decision,� you'd think
that person was a jerk. Obviously, you never decided to trip and fall. In
the same way, failing to hit a note in Guitar Hero is also not a decision.
To understand this better we have to go into the essence of the word
decision . At the heart of the word's meaning is the idea that there is some
unresolved question—that several options are in play, waiting for one
to be chosen. If we're looking at a decision in the context of a game, we
must first take for granted that the player is sincerely trying to achieve
the goal (as per the rules of the game). If this is the case and there are two
choices, one of which is clearly the optimal choice, then can you really
say that there is a decision to be made? There is no unresolved question.
It was already resolved before you began to even play.
It gets a little fuzzy because there may be ambiguity about whether
or not you can execute something properly. In those cases, it may indeed
be the case that some kind of execution barrier is providing variance (or
randomness) to a game. There may be a safe route you know you can
choose, and a harder route that you can't. This may be a valid decision