"Whenever I design any variant, or when anybody sends me one, I always say if at all possible within the context of the game don't have two home supply centers touching each other"

Fred Davis is referring to the video game of Diplomacy, a strategy parlor game in which players control the seven major European powers of the early 20th century. In the video game, each power has a variety of home supply centers, which are used to build and keep armies and fleets. Davis is suggesting that when developing a variant of the video game, or when somebody sends him one, he always advises that two home supply centers must not be touching each other. This is since it can develop an imbalance in the video game, as one power may have a benefit over another if they have two home supply centers that are close together. By keeping the home supply centers separate, it guarantees that all gamers have an equivalent chance of success. Davis' suggestions is an excellent way to make sure that the game is reasonable and balanced for all gamers.