Screenshots
Watch trailer on Steam ↗CM-SS13
CM-SS13 Devs · Published by CM-SS13 Community · Official site ↗
Content notice: This game features frequent pixelated violence and gore. Players should also expect: Low Fidelity: Body Horror, Surgery, Substance Use. And potentially strong language
Mixed — 67% positive (180 reviews) · 12 achievements
Last updated 28 Sept 2026
The year is 2182, but the engine is from 2003. Join the Falling Falcons in a massive tactical deathmatch RP fest held together by spaghetti code and duct tape. Build bases, perform surgery, or evolve as the Hive. It's laggy, it's complex, and it is the most fun you will have dying in space.
Action, RPG, Simulation, Free To Play · 2026 · More free games
Explore CM-SS13's vast universe where you can build, operate, or evolve as the Hive in a mix of action and RPG. Join the Falling Falcons in their intense tactical deathmatches, all while navigating the game's spaghetti code complexity.
About this game
The year is 2182. High Command has dispatched the USS Almayer to the frontier. You are a member of the Falling Falcons - 2nd Company, 2nd Battalion, 4th Brigade.
Your orders are simple: Respond to an unknown distress signal, secure the colony, and neutralise any threats. But on the rim of known space, nothing is ever simple.
BYOND: Build Your Own Net Dream
Built on the ancient, accursed, yet still beloved BYOND platform, this isn’t regular SS13; it's a completely overhauled multiplayer roleplay tactical disaster simulator. It looks like a game from the 90s, plays like a milsim from the future, and breaks like a cheap lawnmower.
Whether you are holding the FOB, performing open-heart surgery in a sand pit, or playing a xenonid trying to figure out how to open a door, your actions define the round. Every bullet must be accounted for, every wound requires surgical precision to treat, every host must be incubated, and every order must move down the chain of command.
KEY FEATURES
Massively Multiplayer: Theoretically high player counts allow for full company-scale operations, meaning lots of people screaming over the radio at once or complaining that the Empress is micromanaging the hivemind.
Complex Medical System: Health isn't just a bar. Treat broken bones, internal organ failure, and overdoses. If the xenonids don't kill you, the medic mixing up the labels on the pill bottle might.
Destructible Environments: Blow open walls with C4, weld doors, or burn down the entire jungle because you saw a spider.
Logistics & Command: The war isn't won by shooting alone. It’s won by the shipside support crew, including the Requisitions Officer, who orders the ammo for your rifle, and the Executive Officer, who really didn't mean to accidentally orbital bombard Delta Squad.
Roleplay First: Immerse yourself in the hierarchy. Follow orders, shout tactical info over the radio, and engage in the unique "culture" of the Falling Falcons.
Emergent Storytelling: Will you hide in a locker for 45 minutes as a suvivor? Will you robust a xenonid with a toolbox? Or will you succumb to liver failure after finding the colony's vodka stash?
Corporate Interests: Roleplay as a Liaison from a shadowy company that cares more about the quarterly profit margins than your survival.
Hostile Third Parties: Sometimes it’s insurgents. Sometimes it’s high-tech hunters. Sometimes it’s just the Military Police arresting you for not wearing your helmet.
⚠️ WARNING: READ BEFORE ENLISTING ⚠️
1. Ancient Technology: This game runs on BYOND. When you click "Play" on Steam, it will install the BYOND requirements for you. Yes, you sometimes will get an popup for Byond Premium when it boots up. Lummox JR has to eat somehow.
2. The Learning Cliff: The controls are not intuitive. You will accidentally shoot your foot. You will drop your gun in the middle of a firefight. You will struggle to open a bag of chips.
The UI looks like the cockpit of a 747-800. Take a moment to read the starter guide, call a Mentor (F1), or just ask the Marine standing next to you how to put your helmet on. We were all bald and confused once.
3. Roleplay Expectations: aka Yes, you have to play as a Character. This is a Medium Roleplay (MRP) environment.
Names: Name your character something believable, not "xx_Headshot_King_xx" or "Obi-Wan Kenobi."
Behaviour: You are a Marine (or a giant bug). Act like one. If you run around griefing your teammates or screaming internet memes in the chat, you will probably hear the dreaded Bwoink. That is one of our volunteer Moderators coming to have a very polite conversation with you about your life choices.
4. The Rules: Read them. They exist to keep the chaos fun, not frustrating. If you break Marine Law, the MPs will arrest you. If you break Server Rules, the Admins will probably ban you without much fanfare.
FULLY OPEN SOURCE
Both the game-code and the launcher are totally open source, and available for anyone to contribute to.
CM-SS13: GitHub cmss13-devs/cmss13 (AGPL, CC 3.0 BY-SA)
Launcher: GitHub cmss13-devs/launcher (GPL)
System Requirements
Will my PC run this? →Minimum
- OS *: Windows 10 (or Windows 7 if you still refuse to update)
- Processor: A potato with a pulse. (Any Dual Core CPU from the last decade. Single-core speed is king here because the engine doesn't know what "multithreading" is).
- Memory: 4 GB RAM
- Graphics: Integrated Graphics. If it can render a spreadsheet, it can render this game.
- DirectX: Version 9.0c
- Network: Broadband Internet connection
- Storage: 500 MB available space
- Additional Notes: A mouse is required. Touchpads are a death sentence.
Recommended
- OS: Windows 10 / 11
- Processor: High-frequency CPU (3.0GHz+). The engine runs on a single core, so throw raw speed at it.
- Memory: 8 GB RAM
- Graphics: Dedicated GPU (Not for the game, but so you can watch YouTube while you wait for the Round Restart).
- Network: Broadband Internet connection
- Sound Card: Any. You need to hear the distinct hiss of a Xenonid behind you.
Supported Languages
*languages with full audio support
Latest news
AnnouncementsOfficial
Build v0.15.1: Sandbox and Overlay
This is pretty much what it says in the title, one feature and one bug fix:Sandbox ModeNo longer do you have to fuss around with Git and Visual Studio Code to launch your own version of the game.This allows you to always have the latest version of the game to experiment with and check out features, while not having to fiddle with development tools.Bug FixesThe Steam overlay would not take up the whole screenspace - this has been fixed (though is still a little janky!)Read full article on Community Announcements (harryob)AnnouncementsOfficial
Build v0.14.1: Linux Support!
Only one real headline feature in this release, and that is:Linux SupportWe now support Linux! No additional setup required, the launcher will configure everything itself to get you connected to the game.Known IssuesApplication size is currently 350mb~. This is smaller over the wire, but will take up this much space on disk. This is the world of packaging for Linux, it's annoying. We're going to look at slimming down the number of libraries we send in a future release.Scrolling in the launcher is a bit laggy.Seems to be an issue with our current distribution method (https://github.com/tauri-apps/tauri/issues/6200), but we'll look into moving away from this to make it a bit more responsive. This is only the launcher, not in game UIs.Almost certainly individual issues with different distros and settings. We'll look into this when we can, but if you have a particularly esoteric setup, it might be difficult to support. Report bugs at https://github.com/cmss13-devs/cm-launcher/issues.All that aside, at least in our testing (on Debian derived distros), it works consistently. We hope it works well for you.Discuss this update on our community forums: https://forum.cm-ss13.com/t/launcher-build-v0-14-1-linux-support/19297Read full article on Community Announcements (harryob)AnnouncementsOfficial
Build v0.13.1 - Fixes and Windows Defender
This is a bug fix only release, addressing a couple of things:Steam wouldn't let you reconnect after a few hours of playing a round, and you would have to reboot the launcherIf you disconnected during the course of usual play, you would be reconnected to the Guest authentication screenThis build is currently only live on the latest branch, as every version we push has to be manually submitted to Windows to remove the Defender warnings you may have encountered, and we have to wait a few days for the whitelisting to be distributed to everyone's devices.A note on Windows DefenderThis application is sometimes captured by Windows Defender's Machine Learning algorithms, which look for applications that have code patterns that look similar to that of actual malware. In our case, this is likely due to the launcher downloading the engine from the internet, then immediately running the executable to connect you to the game.Every new build is manually uploaded to the Defender team, who inspect the file to ensure it is not malware. The exact version of the launcher is then whitelisted, and when your device updates malware definitions, it will no longer be flagged by this exact version. This process has to be repeated anytime we change the .exe.In order to force an update of your definitions, you can navigate to your Virus & threat protection settings, go to Protection updates and Check for updates Apologies for any inconvenience.Discuss this update on our community forums:https://forum.cm-ss13.com/t/cm-launcher-v0-13-1/19281Read full article on Community Announcements (harryob)AnnouncementsOfficial
Steam Release Build v0.12.0
The Steam Wrapper developed by HarryOB handles your BYOND installation and connects you straight to the server. No longer must you deal with Byond versions, the Gooner station filled hub and have to explain to your other friends how to install the default installer. There are a number of improvements in this latest version, including: Achievements Get achievements on Steam as you progress in game. See the Achievements list to get what's available - more may be added! The icons have been graciously provided by thwomper and antlerss on our Discord.Read full article on Community Announcements (Frozentsbgg)AnnouncementsOfficial
CM-SS13 Playtest Release
In preparation for the main launch of the CM-SS13 Steam Launch, you can now enrol in the Playtest through the store page. Access will be granted in daily batches, so make sure to sign up today! Please help us out and report any issues or bugs you encounter with the new launcher in the CM Discord.Read full article on Community Announcements (harryob)
