Goal
Also said as Objective
What the player is trying to make happen. A goal turns every action into a good one or a bad one.
Without a goal, nothing you do is better than anything else, and players drift off. A clear goal gives the player a question to ask of each move: does this help?
Say it
“The player does not know what they are doing here. Put one goal on screen: reach the flag at the top of the tower. Everything else in this level is on the way there.”
Where you’ve seen it
Pong's cabinet gave one instruction: "Avoid missing ball for high score." Six words, and you know what a good move is.
Not to be confused with reward
A goal is what you aim for. A reward is what you are given. A game can have a clear goal and no reward at all besides reaching it.