What is the name of old board game where you try to become dictator?

The board game you're thinking of is called "Diplomacy".

While you don't technically become a "dictator", the goal of the game is to control as much of Europe as possible through strategic alliances and negotiation. Players must build armies and fleets, maneuver them across the board, and negotiate treaties with other players, all in an attempt to gain supremacy.

The game is known for its complex strategy, intricate diplomacy, and potential for betrayals, making it a game where cunning and manipulation are as important as military prowess.