"Communists were first to space, no wonder they are first to master glorious power of fusion."
Fusion Plants are the 11th land generator. The land cost only takes about twice as long to reach than Bombers, Sky Farms, and Laser Drills with the same researcher levels, but they take a lot of comrades to unlock, like Laser Drills, and have the same generator cost of 100 CC. The first mission requiring fusion plants is on Rank 113.
Fusion Plants are currently the final feasibly unlockable industry. Further industries exist in the game ( Air Rescues, Cyborgs, etc.), but their unlock requirements and prices are set so high that almost no one can reach them. Their requirements and prices will be lowered once more ranks are released.