: Over 100 random events—ranging from natural disasters to diplomatic marriages—can shift the game's momentum. "Quests" offer rewards for completing specific objectives within a timeframe, such as building a set number of libraries.

: No longer a late-game afterthought, espionage now has its own economy slider. Investing "Espionage Points" against specific rivals unlocks passive benefits like seeing their research and active missions to sabotage production or steal technologies.

: Founded by Great People in the late game, corporations function similarly to religions. They consume specific resources (like food or minerals) to provide bonuses like extra food or production across your empire, but they also increase city maintenance costs.

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Sid Meier's Civilization IV: Beyond the Sword