Why did a game about settling an island change how the world plays board games?

Because it carried a German style of game, with no knockouts and no direct fighting, to the rest of the world. The Settlers of Catan, published in Germany in 1995, was not the first Eurogame, but it became more successful than any of its predecessors and paved the way for the genre outside Europe. By 2020 more than 32 million boxed sets in 40 languages had been sold.

Its creator, Klaus Teuber, was a dental technician who began designing games as a hobby and then as a career. The genre he joined had its own roots: after the war, partly because of an aversion to products glorifying conflict, strategy and economic games such as Acquire became popular in Germany. Eurogames generally have indirect interaction between players and no player elimination, and they give several ways to score points.

That design choice matters at a game table. In Monopoly a close game can extend indefinitely. Eurogames usually have mechanics that limit the playing time, and balancing rules that slightly help lagging players. Scoring is often arranged so that hidden points or end-of-game bonuses can lift a player who seemed to be losing.

Catan shows this in miniature. The island's hexagonal tiles are laid out randomly each game, players trade cards with each other, and the first to ten victory points wins.