1. A non-transitory computer-readable medium with a game control program embedded thereon to be implemented by a computer system, the game control program comprising: an arrangement module configured to arrange an object in a three-dimensional space provided in a game field and store data indicating a position of the arranged object in an object database; a simulator module configured to simulate a physical phenomenon on the three-dimensional space by simulating a physical phenomenon on a two-dimensional plane onto which the three-dimensional space is projected, disregarding a direction of one of dimensions of the three-dimensional space, and by reflecting a result of simulation in the disregarded direction; and a control module configured to apply the simulated physical phenomenon on the object in the three-dimensional space, wherein the simulator module configured to simulate a physical phenomenon retrieves, from a storage unit that stores a value of physical characteristic in each of a plurality of meshes, each mesh obtained by dividing the two-dimensional plane into a plurality of computational meshes, a value of physical characteristic in a mesh and a value of physical characteristic in a surrounding mesh thereof, to calculate the value of physical characteristic in the mesh based on the value of physical characteristic in the surrounding mesh, and to store the calculated value of physical characteristic in the storage unit; the arrangement module arranges a spore of mycelia for decomposing the object and an ignition item for burning the object in the three-dimensional space, and stores data indicating a position of the spore and the ignition item in the object database; the simulator module includes a mycelia growth simulator configured to refer to the object database, allow the mycelia to grow from the spore in accordance with a predetermined condition for growth, and store distribution of the mycelia in the storage, and also includes a temperature distribution simulator configured to refer to the object database, cause the ignition item to ignite the object in accordance with a predetermined condition for burning, and store distribution of temperature in the three-dimensional space in the storage; when the arrangement module arranges the spore in the three-dimensional space, the control module causes the mycelia growth simulator to simulate growth of the mycelia, deletes data for the object that has been in contact with the mycelia for a predetermined period of time from the object database, determining that the object is decomposed; and when the arrangement module arranges the ignition item in the three-dimensional space, the control unit causes the temperature distribution simulator to simulate distribution of the temperature and deletes data for the object that has reached a predetermined temperature, the predetermined temperature being associated with the object, from the object database, determining that the object is burned.