game(Name, Type, Manufacturer, Difficulty).
game('Space Invaders', 'Arcade', 'Arcade Masters', 1).
game('Space Invaders II', 'Arcade', 'Arcade Masters', 2).
game('Space Invaders III', 'Arcade', 'Arcade Masters', 3).
game('Racing Thunder', 'Racing', 'GameTech', 2).
game('Racing Thunder: Turbo', 'Racing', 'GameTech', 3).
game('Dance Revolution', 'Music', 'Digital Dreams', 1).
game('Pinball Classic', 'Pinball', 'RetroPlay', 2).
game('Zombie Shooter', 'FPS', 'Arcade Masters', 2).
game('Basketball Pro', 'Sports', 'GameTech', 1).category(Game, Category).
category('Space Invaders', 'Shooter').
category('Space Invaders II', 'Shooter').
category('Space Invaders III', 'Shooter').
category('Racing Thunder', 'Sports').
category('Racing Thunder: Turbo', 'Sports').
category('Dance Revolution', 'Rhythm').
category('Pinball Classic', 'Physics').
category('Zombie Shooter', 'Shooter').
category('Basketball Pro', 'Sports').category_parent(Category, ParentCategory).
category_parent('Shooter', 'Action').
category_parent('Sports', 'Physical').
category_parent('Rhythm', 'Music').
category_parent('Physics', 'Simulation').
category_parent('Action', 'Game').
category_parent('Physical', 'Game').
category_parent('Music', 'Game').
category_parent('Simulation', 'Game').sequel(Game, SequelGame).
sequel('Space Invaders', 'Space Invaders II').
sequel('Space Invaders II', 'Space Invaders III').
sequel('Racing Thunder', 'Racing Thunder: Turbo').player_plays(PlayerName, Game).
player_plays('John', 'Space Invaders').
player_plays('John', 'Basketball Pro').
player_plays('Sarah', 'Pinball Classic').
player_plays('Mike', 'Space Invaders').
player_plays('Mike', 'Space Invaders II').
player_plays('Mike', 'Space Invaders III').
player_plays('Emma', 'Dance Revolution').
player_plays('David', 'Racing Thunder').
player_plays('David', 'Racing Thunder: Turbo').
player_plays('Lisa', 'Zombie Shooter').