What is the theme of Risk board game?

The theme of Risk board game is world domination.

Players compete to conquer the world by strategically deploying armies, attacking territories, and ultimately eliminating their opponents.

While there isn't a specific narrative or backstory woven into the game, the mechanics and goal clearly point towards a global conquest scenario. The board is a stylized map of the world, and the game is all about acquiring territory, power, and ultimately, victory.