Reactor cropped

A UNSC Reactor.

“UNSC Reactors provide the energy needed to access the advanced buildings, units and technology upgrades.”
— In-game description[1]

The Reactor is a UNSC structure. It appears in Halo Wars.


UNSC Reactor 3Renders

Different views of the UNSC Reactor.

A UNSC Station is powered by a small Hydrogen reactor which allows it to operate some pretty sophisticated systems. In order to set up a base quickly, it is very small, but these power plants are modular. As you expand your base of operations and field more complicated weapon systems you will require more power. Base sockets can facilitate the addition of larger hydrogen reactor units which provide the electricity to allow you to field more and more sophisticated weaponry. These additional reactors built into your base sockets are even modular and can be upgraded, by using some of your supplies, to double their output.


Defend your base reactors at all costs. They are priority targets for enemy raids. When they are destroyed, you will no longer be able to produce your heavy hitting Scorpions, Vultures or other and aircraft. Without these Reactors, the Covenant or any other human players can finish you quickly and rebuilding is both costly and time taking.[2] Buying additional reactors will always be cheaper then upgrading them, but can take up to 4 building sites (for max tech level). This can be detrimental on maps with limited base building real estate available.


In game, reactors increase the technological (amount of energy units) level of the UNSC, which allows them to field heavier and more advanced units. To explain, for each unit, building and upgrade of the UNSC, a certain number of energy units is required to make use of it. Typically the most advanced of units/upgrades require more energy units than less advanced ones. Each reactor constantly provides at least one energy unit, and will continue to do so until it is destroyed. At an expensive price of 1200 resource units, a default reactor can be upgraded to an advanced reactor, which provides the an output of power equal to two default reactors, or two energy units. Naturally, Reactors are an invaluable element for the UNSC in Halo Wars; without them, they are limited to basic infantry and Warthogs.


Basic Reactor: 250 supplies for the first reactor, 500 for the second, 750 for the third, and 1,000 for any subsequent ones built. Increases tech level.

Advanced Reactor: 1,200.


  • When even slightly damaged from enemy fire, Reactors can be seen venting a blue cloud and a blue liquid.
  • In campaign missions Arcadia Outskirts and Dome of Light, abandoned ONI reactors can be captured and garrisoned to provide free tech. They are functionally identical to the Forerunner bonus reactor, providing +1 tech each and being un-upgradable; each mission contains 2 so upgradability isn't an issue.



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