Expansion games can be called flooding games, contamination games or spreading games. Often you have a virus and you want to contaminate as many cases as possible. These games are generally turn-based. In each round, you have to choose what will be the next color contaminated. Once you have selected a color, all the squares adjacent to the current cell of the chosen color will be yours. The game continues until you have no more turns left. The goal is to contaminate the entire grid in a minimum of turns.