A non-limiting example game system includes a processor incorporated within a main body apparatus, and the processor creates, based on operation inputs of a player, a game stage by selecting components corresponding to a virtual room and by arranging panels corresponding to the components on a grid-shaped arrangement area. In the virtual room, a passage, a stairs, a door with lock blocking the passage and a treasure chest are arranged. A key for releasing the door with lock is contained in the treasure chest. The player creates the game stage by connecting all of the passages and the stairs from a start room that a game is started to a room where a boss enemy object is arranged and by taking arrangement of the doors with lock and the treasure chests containing the key into consideration.