Gameplay is a huge amount of variables converging in to one emotional experience. This could be created by a humongous amount of factors and lead to any number of emotions; sadness, frustration, anger, achievement, happiness, love, fear, disgust… the list goes on.
Gameplay is different from reading a book, or watching a film. YOU make the choices, not Johnny Depp. You chop the heads off, you run over the women, you save the baby for the burning building. Or you choose not too. Then you are left with the consequences. Films don’t make you feel pangs of guilt. That’s why games must be seen in a slightly different light than other media. You are involved.
It represents the potential for breathtaking beauty and sensory overload. It can be created/expanded upon using an element of choice. Fallout, in my opinion, creates a good contrast of good and evil. Chosen the light path? You gain respect and side quests are revealed whilst characters feel safe in your company. Become too good and certain dodgy types do not trust you, taking away big opportunities. Choose the dark side and gain extra exp for the kills, but citizens turn on you and people will not trust you with messages and items.
Gameplay is an experience that depends on the type of player you are. I hate time trials, I don’t play well under major time pressure and it becomes a bad gameplay experience for me. My boyfriend how ever excels in being timed and spends hours beating top scores, and gaining medals. Things like characters, game controls and storyline are all very important things, but in the end it is how you the player find the game. Did you ENJOY it? Was it FUN? Yeah? Then that's good gameplay for you.