Side Effects Guaranteed is part one of a two-part story expansion for Obsidian's sci-fi RPG. It costs $14.99, adds a whole new region of Eden, and the choices you make carry into part two in spring 2027.
Obsidian is going back to Arcadia, and it’s bringing a puddle. The Outer Worlds 2’s first story expansion, Side Effects Guaranteed, launches December 2 for $14.99, and it’s a lot more than a side quest pack. It raises the level cap from 30 to 36, adds 15 new perks, four new flaws, a brand-new region of Eden, new enemies, new gear, new companion outfits and a whole new radio station.
Xbox laid it all out today in a post on Xbox Wire from Mikey Dowling, Xbox’s Director of Communications and Franchise. This is part one of a two-part narrative expansion, and part two is already on the calendar for spring 2027. Xbox says “choices made will directly impact the next DLC,” which is exactly the kind of promise that makes an Obsidian RPG worth sinking another weekend into.
Side Effects Guaranteed is part one of a two-part narrative expansion heading to The Outer Worlds 2 on December 2, introducing a level cap increase, new perks, flaws, weapons, armor, and more. https://t.co/yUlb8YRBDO
, XBOX Wire (@XBOXWire) November 10, 2026
A heist gone very, very wrong
The setup is pure Outer Worlds. A distress signal pulls you and the crew of the Incognito to a derelict ship, where the crew is frozen in suspended animation and something nasty has clearly happened to at least one of them. A video message from the ship’s captain explains that her people were contaminated during a heist with something that causes “explosive cell death” unless they find a cure. She then clarifies that she means “more like a… ‘liquefaction’.” The puddle on the floor backs her up.
That message leads you to Gordon Hazen, one of the top agents in Sub Rosa, a criminal outfit of people who chose to steal from the factions instead of working for them. Gordon sends you to Elysium Valley, a new region on Eden that’s home to a settlement of former Protectorate subjects their own leaders forgot about. He thinks they hold the cure. Gordon prefers diplomacy, but he wants the answer however you get it.
He’s not the only Sub Rosa agent in the valley, either. Algernon Lankester wants to recruit you to exploit those forgotten subjects for his own gain. Per Xbox, the fate of the subjects, the frozen agents and Sub Rosa itself is all up to you. Two rival bosses, a desperate community and a cure everybody wants is a setup built for the kind of branching consequences The Outer Worlds 2 already does better than almost anything in the genre. Our own review gave the base game a 10/10 for exactly that: choices that reshape the story instead of just nudging it.
Level 36, 15 new perks and flaws that bite back
The systems side is where this expansion earns its price. The level cap climbs from 30 to 36, which means more skill points and room for three more perks, drawn from a pool of 15 brand-new ones. That’s a real reason to load up an endgame save and keep tuning a build.
The four new flaws are the fun part, because Outer Worlds flaws always come with a catch. Lethally Tolerant raises your max toxicity thanks to all those chemicals you’ve been abusing, but if you ever hit a Toxicity Crash, you die instantly. Must Have Been the Wind marks an “assassination target” in each combat group. Kill that target and you get a 20% damage and speed buff until the fight ends. Fail, or hit someone else first, and you eat a 10% damage and speed debuff for 30 seconds. That’s a flaw that rewards stealth players and punishes anyone who panics and starts spraying, and we love that it changes how you approach every encounter instead of just sitting in a menu.
Elysium Valley also brings new threats, including vicious canids and primal sprats. Xbox describes those as “Just a normal sprat, but about 100 times the size.” If you spent the main game casually blasting the little ones around Arcadia, payback is coming.
On top of that, Side Effects Guaranteed adds new weapons and armor, new outfits for every companion, and a Sub Rosa-run radio station with 20 new songs.
You can jump straight in
One smart touch: you don’t need a late-game save to play it. The expansion adds a new alternate starting point on the main menu when you start a new game. It loads a custom save that drops you right at the beginning of the DLC, lets you spend your skill and perk points, and sends you off. That’s a great call for anyone who finished the campaign on another profile, or who wants to see the new content without replaying the whole campaign first.
Price and how to get it
Side Effects Guaranteed costs $14.99 on its own. It’s also included in The Outer Worlds 2 Premium Edition and the Premium Edition Upgrade, so if you already own the Premium Edition, December 2 is just a download. The Outer Worlds 2 is on Xbox Series X|S and PC, and it’s on Game Pass, so members already have the base game ready to go.
For an Xbox first-party RPG that already landed as one of the best games Obsidian has made, a two-part story expansion with a real level cap increase, new build tools and choices that carry forward is exactly the kind of support players want. Fifteen bucks for a new region, a new faction drama and six more levels feels like a strong deal, and the fact that part two is already dated for spring 2027 tells us Xbox and Obsidian are in this for the long haul.
Image: Xbox
Sources
- Xbox Wire: Side Effects Guaranteed in the First DLC For The Outer Worlds 2, Coming December 2 (Mikey Dowling, Nov 10, 2026)
- @XBOXWire on X (Nov 10, 2026, 1:02 PM ET)
- OnPoint 4 Gamers: The Outer Worlds 2 Review
Level 36, new flaws, a puddle mystery. Are you jumping into Side Effects Guaranteed on December 2?
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