In Collins, Incollables is a game of strategy and back-and-forth diplomacy between two countries, Decay and construction. One player is the country Decay, who has been known to take advantage of the situation to build whatever is necessary to prevent the other country from becoming ever-vanishingly strong. The other player is called Decay, who has been forced to build what he can and watch as the other country Decay begins to vanish. The game is played on a map with the available land divided into five Categories: Mountains, Plains, Hills, Rivers, and Kills. The player to survive the most of the game's course, together with the card game and puzzle game, will be the winner.