Storage medium having game program stored thereon and game apparatus

A storage medium having stored thereon a game program executable by a computer of a game apparatus for displaying a virtual game world, in which a player character whose motion is controlled by an input signal from an input device in accordance with an operation performed by a player appears as well as a plurality of objects, as a game image on a display screen, the game program causing the computer to execute:

• a determination area setting step of setting a first collision determination area and a second collision determination area moving concurrently with the motion of the player character;
• a collision detection step of detecting a collision of one of the first collision determination area and the second collision determination area against an object among the plurality of objects;
• a first influence determination step of, each time the collision detection step detects a collision of the first collision determination area against an object, determining an influence, to be exerted on the object which has collided against the first collision determination area, as being one of a plurality of preset influences at a predetermined probability;
• a second influence determination step of, each time the collision detection step detects a collision of the second collision determination area against an object, determining an influence, to be exerted on the object which has collided against the second collision determination area, as being a predetermined influence;
• and
• a display state changing step of changing a display state of each of the influenced objects to a display state in accordance with the influence determined by each of the first influence determination step and the second influence determination step.