Review scores are relative to the price and category of the game and not entirely comparable between different games.
Score types explained in brief:
Visual - Score represents the overall graphical quality of the game, including visual style, readability, functionality and reviewer personal preference.
Audio - Score represents the quality of all audio, including voice acting, music, sound effects etc, both in terms of quality and clarity.
Story - Score represents the quality of writing in the game, including dialogue, written content and ambient storytelling.
Gameplay - Score represents the playable functions of the game, including control, basic mechanics and their implementation and other extraneous gameplay components.
Overall - Score represents the overall enjoyment and value of the game as a full experience and is not an average.