Changes made to the parameters in the middle of a run take effect immediately. The game board shows a map of the planet flattened out into a square. If a fish or shark moves off one edge of the map, it will reappear on the other side. At the start of the game, fish and sharks are placed randomly around the board. You control how many are there at the start through the options menu.
Fish move onto the next adjacent space, chosen randomly.
After all fish and sharks have moved once, the scoreboard will be updated to show the current population. The movements for the next chronon will then begin. There is also information about the different graph types and a brief introduction to population ecology. These should be addressed to me at the address below. There are numerous improvements that could be made in this game, both in the presentation and in the actual mechanics and assumptions.