Konstantin Fomin of Riot Pixels gave a positive review, rating it at 80% and declaring that it would 'take you on a rollercoaster ride'. Sunset Invasion received mixed reviews from critics. Initial reactions to the DLC noted it as the first alternate history DLC created by the Paradox Development Studio.

The DLC was announced on October 31, 2012, and released on November 15 of that year. The DLC added an Aztec culture and religion to the game, as well as an 'Aztec disease'. The feature was created as a way to counterbalance the invasion of the Mongol Empire, which usually conquers large sections of the eastern half of the game map while leaving the west untouched. Sunset Invasion adds a fictional event where the Aztec Empire invades Europe.