A game device includes: an image processing unit operative to display a screen image of a game field including vertical land features; a passage forming unit operative to form a passage in the game field through which fluid can move, in accordance with an instruction by a user; fluid control unit operative to control fluid supplied to the passage; and a terrestrial character control unit and an aquatic character control unit operative to control an action of a character disposed in the game field. The aquatic character control unit moves the character, which exists in the passage in which the fluid exists, together with the fluid when the fluid is moved along the passage to a lower position by the fluid control unit.