The mod is the prime example. This mod doesn't change the UI language, but rather the social dynamics. It adds five exclusive language groups to the game (Simlish, Sulani, Selvadoradian, etc.). If your Sim moves to Sulani, they may not understand a Sim from Windenburg until they learn the language. This adds an "exclusive" layer of gameplay, effectively "unlocking" language as a strategic feature rather than just a visual setting.