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Atomic Heart: add-ons and the Atomic Pass season pass for Steam
Atomic Heart is an explosive first-person shooter with RPG elements from studio Mundfish, released on February 21, 2023 under publisher Focus Entertainment. It's set in an alternate 1955 Soviet Union where robots, floating cities and a neural network are part of everyday life — until everything goes off the rails. You play as Major P-3, sent to the secret Facility 3826 to find out why the obedient machines suddenly started killing people. The atompunk aesthetic, a fully voiced talking glove and an arsenal of improvised weapons made it one of the most recognizable games to come out of Russia in recent years.
What exactly you're buying here
First things first: this page sells the add-ons, not Atomic Heart itself. To run any DLC or the season pass, the base Atomic Heart must already be owned and installed on your Steam account. The code activates extra content on top of the game — without the base it lands in your library but there's nothing to play. If you don't own the base game yet, get that first, then come back for the pass or a single DLC.
Atomic Pass — all four add-ons in one key
Atomic Pass is the season pass that unlocks all four Atomic Heart story add-ons at once. As of June 2026 every one of them is out, so the pass unlocks the full set with no waiting:
- Annihilation Instinct (August 2, 2023) — P-3 loses part of his combat abilities and enters a new complex where he picks up a fresh arsenal, including a polymeric glove and a snappy melee weapon.
- Trapped in Limbo (February 6, 2024) — a surreal, arcade-flavored episode: a warped reality inside Limbo, unusual physics and an unexpected shift in the rules.
- Enchantment Under the Sea (January 28, 2025) — the underwater Neptune research center, two new weapons and the main plot pushed deeper, now below the surface.
- Blood on Crystal (April 16, 2026) — the final add-on and the conclusion of P-3's story: over eight hours of content, a return to the heart of Facility 3826 and a decisive showdown with the rogue AI ahead of the upcoming sequel.
If you want the whole story through to the end, the Atomic Pass makes more sense — and costs less — than buying the chapters one by one.
Enchantment Under the Sea on its own
If the only chapter you care about is the underwater one, you can grab it as a standalone DLC. Enchantment Under the Sea sends P-3 into the flooded Neptune research center: new locations, enemies and a couple of new weapons — the Thunderclap, a motorized buzz saw that ramps up damage with an electrical charge, and the KM-4 Kuzmich, a double-barrel shotgun with customizable spread. It's the third add-on and, like the rest, it requires the base Atomic Heart to be installed.
How to activate the key in Steam
After ordering you receive a code. Open the Steam client, choose "Games" → "Activate a Product on Steam" from the top menu, enter the key and confirm. The add-on attaches to your installed Atomic Heart: the Atomic Pass unlocks all four DLC at once, while the standalone Enchantment Under the Sea adds its chapter. Launch the game and pick the new content from the in-game menu. Codes usually arrive quickly, but we don't promise hard deadlines — keep an eye on your order status.
Key region
The key is issued in the ROW (Rest of World) region. That means it's meant for a wide range of countries but is still a regional key — in certain excluded regions activation may fail. Check your Steam account region before buying, and if you're unsure about compatibility, it's best to ask in advance, before paying.
Similar games
Into bleak worlds built on post-Soviet and alternate-history ruins? Take a look at Metro Exodus — an atmospheric trek across a scorched Russia. For brutal survival in the Zone, there's S.T.A.L.K.E.R. 2: Heart of Chornobyl. And if it's the ideological-utopia aesthetic with an immersive sim underneath that hooks you, the genre classic BioShock Infinite is right there.
The short version
Atomic Pass is all of Atomic Heart's story content in one key; Enchantment Under the Sea is a standalone underwater chapter. Both are add-ons that need the base game installed, ship as ROW-region keys and activate through Steam. Pick the option that fits your goal and check your account region before buying.
💚 Same game — another format
Nearby in the catalog: Atomic Heart as a Steam gift.