In The Alters, the primary objective of the entire Project Dolly space expedition is to retrieve Rapidium — a unique and mysterious substance known as “the time-traveling element,” found on the planet where Jan Dolski finds himself stranded. Little is known about Rapidium at the start of the game, aside from its miraculous ability to rapidly accelerate organic growth due to emitting a unique type of radiation.
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Obtaining Rapidium allows Jan Dolski to create Altered versions of himself, growing a full human from his DNA sample in just 10 hours, which could revolutionize humanity's approach to medicine, agriculture, and many other fields. The potential of Rapidium is described as almost limitless.
To successfully bring Rapidium back to Earth, Jan is tasked by Ally Corp with building Rapidium Arks. This guide will explain everything players need to know about Rapidium Arks, as well as how many of them they should build in The Alters.
Spoiler Warning: this guide delves into some late-game events, including optional endings to the game. Proceed with caution.
Rapidium Arks in The Alters, Explained
As described by Terrence Maxwell in The Alters, Rapidium is a very volatile and unstable substance that constantly changes its chemical structure, making it almost impossible for the matter not to decay during a lengthy space trip. To preserve Rapidium's properties, he tasks Lucas with sending Jan blueprints for the Rapidium Ark — a hermetic module designed specifically for storing and transporting Rapidium.
After Maxwell asks players to build a Rapidium Ark for the first time during Act 1, they'll receive a main objective to gather materials and build it. Each Rapidium Ark requires a fixed amount of resources to build (30 metals, 120 Rapidium, 100 organics) and must be connected to other modules inside the base. It's implied that each Ark stores 120 Rapidium.
Rapidium Arks are one of the very few base modules that players can't enter. By extension, this means they never malfunction, require no repairs or maintenance, and are never damaged during magnetic storms.
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How Many Rapidium Arks Are Needed?
Only one Rapidium Ark is mandatory to build in The Alters, ensuring the success of Jan Dolski's mission. However, later on, Lucas contacts Jan and asks him to build more, explaining that humanity will benefit greatly from as much Rapidium as Jan can collect. Therefore, it's up to the players to decide how many Rapidium Arks to build, as all additional Arks are marked as optional tasks.
Adding more Rapidium Arks requires researching and building base expansion upgrades first (a total of four), even if there's more than enough space to place the Ark. After each new Ark is built, players can contact Lucas and share the news with him.
Every additional Rapidium Ark unlocks a dedicated achievement in the game.
If players build more than two Rapidium Arks during their playthrough (the more, the better) and take the time to talk to Lucas whenever possible, they can ask him for help near the game's ending to hack the rescue ship and land it with the Alters outside of Ally Corporation's reach, essentially unlocking the third ending path besides Maxwell's or Lena's ending.
Building a total of five Rapidium Arks (one for each of the base extension tiers) completes the optional Ark task chain and grants the “Exceed All Expectations” achievement.
While players can continue building as many Rapidium Arks as they want after reaching five (no further base expansion is needed beyond that), there's no gameplay benefit to doing so. Any Ark built after five is only recommended for players who have extra resources to spare and are curious to keep building more to see how many they can construct before finishing the game.
The Alters
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OpenCritic Reviews
- Top Critic Avg: 86 /100 Critics Rec: 94%
- Released
- June 13, 2025
- ESRB
- Mature 17+ / Blood and Gore, Strong Language, Use of Drugs and Alcohol, Violence
- Developer(s)
- 11 Bit Studios
- Publisher(s)
- 11 Bit Studios
WHERE TO PLAY
- Genre(s)
- Survival, Strategy, Management
- Platform(s)
- PC, PS5, Xbox Series X, Xbox Series S
