The Manhattan Project: Second Stage consists of four small expansions that can be added to the base game individually or together.

• Nations 2 works like the previous Nations expansion with each player getting one card to represent a country and gain a special power. Seven new countries and powers are represented.

• Rocket Technology allows you to build a rocket factory when taking the Design Bomb action. Rockets work exactly like bombers - but fighters provide no defense against them.

• H-Bomb Technology upgrades the Design Bomb action allowing a player to return an available bomb to the bottom of the deck in order to acquire an H-Bomb card. To build an H-Bomb however the player needs Lithium Deuteride which comes from new cards that work similar to Mines.

• Personalities adds seven roles to the game based on real individuals who contributed to the Manhattan Project. Each time you retrieve your workers you will select a different role. Each role will grant you persistent benefits until the next time you retrieve.