1. A video game apparatus for advancing a game in a virtual space where a player character which acts according to an operation by a player and two or more non-player characters exist, respectively different parameters being set on the non-player characters, the non-player characters being comprised of a group of the non-player characters belonging to the player character's own party and another group of the non-player characters not belonging to the player character's own party; the player character instructing a task to the non-player characters belonging to the player character's own party and getting at least one participant character, which is selected from the non-player characters belonging to the player character's own party, to execute the instructed task; the game being advanced according to a result of the task executed by the participant characters the apparatus comprising: a memory that stores a plurality of the tasks which the player character can get the non-player characters belonging to the player character's own party to execute in association with a scenario development of the game; a task display system that displays the tasks on a display so as to be selected by the player, when the scenario development of the game reaches a predetermined position, the tasks to be displayed being determined by referring to the memory; a candidate character selection display system that determines candidate characters from the non-player characters belonging to the player character's own party, the candidate character being possible to participate in the task selected among the displayed tasks by the player through input means and displays the determined candidate characters on the display so as to be selected by the player; a participant character determining system that determines the character selected by the player through the input means from the candidate characters as the participant character, which executes said selected task; and a task execution system that executes the task according to the parameter which is set on the participant character on the basis of the determined participant character and the selected task.