Final answer:
The key figure in relation to The Lego Movie Video Game is Emmet, an ordinary LEGO mini-figure who leads the adventure.
Step-by-step explanation:
The key figure in relation to The Lego Movie Video Game refers to the main character or protagonist around which the game's storyline revolves. The central character in this game is Emmet, an ordinary LEGO mini-figure, who is mistakenly identified as the most extraordinary person and the key to saving the world from an evil tyrant. Players guide Emmet and a host of other characters through a series of adventures in a storyline that's closely tied to the plot of The Lego Movie.