“Our ancestors harnessed the power of a sun, and so again shall we.”
— Commissioner Pravin Lal, “The Science of Our Fathers”
In SMAC’s future history, the height of human technological achievement on Earth is represented by the UN Starship Unity. Thematically, this is what ties the game together with the Civilization series. The scientific win condition in those games has always been to build a ship capable of colonizing another world.
This makes for an interesting contrast with the previous games. See, the Civilization series traditionally takes a Whiggish view of history. Every technological breakthrough makes your civilization stronger and more capable in some way or another. And in particular, the player’s civilization is almost always going from one triumph to the next. If for some reason it isn’t, the typical player will turn the difficulty down until that’s true. So the usual experience of these games in single-player mode is the headiness of uninterrupted exponential growth.
But in SMAC, the colonists start in something of a Dark Age. They live with the legacy of a civilization that was more sophisticated than their own, while knowing that it eventually ended in unambiguous, catastrophic failure. All the factions are therefore intensely dedicated to doing it better next time.
The engine that gave the colonists their second chance was powered by the very stuff of the stars themselves: fusion. So the re-development of reliable fusion power on Planet is a huge milestone. It establishes that the sixth-tier of the tech tree is where the colonists finally feel as if they have matched their ancestors. When they look to the future, they are no longer also necessarily looking to the past.
Reynolds goes out of his way to mark the occasion in both the narrative and the gameplay. First, he chooses Lal to speak, as he is the one who will seek to place his current events in historical perspective. But then he has him do nothing more than elegantly state the core fact. Man once had the sun’s power at his fingertips; now he does once more. It’s beautiful.
And then Reynolds makes sure the gameplay backs this up. Fusion Power is one of the very most desirable technologies in the game. It’s not as good as Industrial Automation, but it’s certainly in the next tier under that. Based on Pre-Sentient Algorithms and Superconductors, it allows the creation of Fusion Labs (which multiply both energy production and science) and replaces the Technician specialist with the new Engineer, who produces three energy and two labs simultaneously. In SMAC, money and science are usually set up to trade off, so a technology that helps make both at once is pretty great.
But that’s not even close to the best part. It also unlocks the fusion reactor in the unit design screen, allowing the player to replace their old fission-based designs. Better reactors do a few things that aren’t immediately obvious, but that add up to be a really big deal.
First, the HP of a unit is determined by its reactor level multiplied by ten. Up until now, every unit had 10 HP since fission reactors are level 1, so it isn’t immediately obvious to the player why HP is important. Other than that it’s noticeable that injured units lose more than it seems they maybe should. That’s because the game evaluates combat by building a ratio out of the combination of the attacker’s modified strength and the defender’s. Then it runs rounds of combat by generating random numbers and deducting an HP from the unit whose number didn’t come up. When someone’s out of HPs, they’re dead.
So, for example, if you have a four-strength attacker fighting a two-strength defender, two-thirds of the combat rounds will end up with a hit on the defender and the other third of the time the attacker will take the hit. The chances of the defender scoring ten hits before the attacker gets his ten are a lot lower than the 33% chance per round it might look like the defender has on the surface.
But fusion units have double the HP! Which means that even if the other guy has the better weapons, he has to win twice as many combat rounds every time in order to kill a unit. A seemingly technologically-even fight suddenly becomes a total blowout when one side gets fusion power. Because of the way chained probabilities work, it’s way, way better than twice as good to have twice the HP.
The range for air units also depends on their reactor level. So fusion-based aircraft get a couple extra bonus moves. This is a nice quality-of-life benefit, but not one that’s usually game-breaking.
Finally, the equation for unit cost is usually a function of the weapon, armor, chassis type, and special powers of the unit. So, for instance, infantry are cheaper than rovers with the same weapons. And better guns are pricier. But better reactors don’t make the unit uniformly more expensive. Instead, they add a fixed cost but then reduce the cost of the associated weapons and armor.
So this means that really weak units are cheapest with fission reactors. But units fielding weapons (or weapon-equivalents like terraforming modules) that are state of the art when fusion power comes online are actually significantly cheaper than their fission equivalents. The faction with fusion power can not only suddenly build way more effective units, they’re actually even cheaper than their more primitive rivals. The overall effect is unmistakably huge.