Ndemic Creations just dropped Update 1.23 for Plague Inc: Evolved, along with a big paid expansion called Aliens & Anti‑Vaxxers. The update brings a free new scenario, Leprosy, which everyone can play right away. Meanwhile, the DLC shakes things up with a brand-new plague type and six unique scenarios that change how you approach the late game, both in strategy and story.
What’s free right now - Leprosy
Leprosy is part of Update 1.23 and is available for free to all players.
In this scenario, you'll need to navigate modern treatments, long incubation times, and social stigma to make the disease headline news again. It’s all about slow, careful spreading and playing the long game with patience and strategy.
Aliens & Anti‑Vaxxers DLC Overview
- Xenolith takes center stage in the DLC: it’s an alien crystal plague that feels completely different from anything you’ve faced before. With new mechanics, interstellar genes, and unique ways to win, it brings a fresh challenge. The DLC’s vibe swings from conspiracy thriller to full-on apocalypse, mixing sci-fi elements with a dark sense of humor.
- The expansion also includes six new scenarios from Anti‑Vax, Hell On Earth, Zombies Vs Earth, Measles, Herd Immunity, and Cure Mania. Each packed with new gameplay twists, story hooks, and strategic challenges that push you to rethink your usual tactics.
Patch notes highlights and fixes
Update 1.23 brings quality-of-life tweaks and bug fixes to make the new content run smoother. It fixes tutorial blockers, sorts out progression problems in Cure Mode, and tweaks how some mechanics work with cure bubbles and speedrun scoring. The developers have also released quick hotfixes to tackle localization glitches and multiplayer display bugs.
Notable mechanics in Xenolith and scenarios
Xenolith mechanics: This alien crystal plague reshapes the battlefield by altering environments, calling down meteors with gravitational quirks, and unleashing EMP blasts or continent-wide strikes. Players have to juggle massive destruction while fending off human defenses (G-COM).
Anti-Vax turns the usual cure race on its head by spreading misinformation and sabotaging vaccination efforts. Meanwhile, Zombies Vs Earth ditches the viral/cure cycle altogether, replacing it with a relentless, marching threat. These scenarios switch up the win conditions and push players to think differently about strategy.
Developer stance on giveaways and special cases
Ndemic has a history of making DLC temporarily free, they did this with Plague Inc: The Cure during the COVID pandemic. They’ve also said they’d do something similar if Earth ever faced a real alien invasion (which they define as a military attack to take over the planet). It’s an unusual but refreshingly honest note they included with the announcement.
Quick tips for players
Start with Leprosy to get a feel for slow, steady infection tactics and how stigma and treatments shape the spread.
Give Xenolith a try on easier settings to get to grips with its unique resource system (XNA) and how human defenses (G-COM) respond.
Dive into the new scenarios to discover how their story-driven challenges push you to rethink your usual strategies. Anti-Vax and Herd Immunity especially reward fresh, unconventional approaches.
Final Takeaway
Update 1.23 delivers fresh content to all players with the new Leprosy scenario, while the Aliens & Anti‑Vaxxers DLC pushes Plague Inc’s boundaries with daring, genre-mixing mechanics and scenarios. Whether you’re into slow, realistic simulations or wild sci-fi disasters, this update expands the game’s strategic and storytelling possibilities. Plus, it’s backed by quick fixes to keep everything running smoothly. For the full scoop and detailed patch notes, check out the official announcement.