Abiotic Factor Co-op: Online Session vs Dedicated Server
Quick answer: There are two ways to play Abiotic Factor co-op. An in-game online session (pick Enter the Facility, uncheck single-player, invite via Steam or session code) is fastest but only runs while the host is playing. A dedicated server keeps the facility online 24/7 so anyone can drop in whenever, even when the host is offline. The game you play is Steam App 427410; the dedicated server tool is a separate Steam App 2857200.
The two ways to play co-op
| Option | How it works | Best for |
|---|---|---|
| In-game online session (non-dedicated) | One player hosts from inside the game. The world only exists while that player is in the game. | Same-evening sessions where everyone plays together |
| Dedicated server | A separate headless program runs the world. No one has to be playing for the world to stay up; the machine just has to stay on. | Time-zone-split groups, drop-in play, persistent bases |
Option 1: Host an in-game online session
This is the built-in co-op and the right choice for most groups starting out. No SteamCMD, no port forwarding required if you invite through Steam.
- Launch Abiotic Factor from your Steam library (the normal game).
- Select Enter the Facility, then load an existing world or create a new one.
- In the world setup menu, uncheck the single-player option so the world allows other players to join.
- Once in the world, press Esc and either invite friends through your Steam friend list, or reveal and copy the session code for them to enter.
- Friends launch the game, choose Join a Server, and accept the invite or paste the code.
Crossplay: press Esc while hosting, open the Gameplay tab (the human-with-nodes icon), and toggle the Crossplay option so PS5 and Xbox players can join. Players can join a running session at any time, even hours in.
The catch: the world only lives while the host is in the game. The moment the host closes Abiotic Factor, the session ends and no one can play until the host comes back online. That single limitation is what drives most groups toward a dedicated server.
Option 2: Run a dedicated server
A dedicated server is a separate, headless program. It holds the world open around the clock, so any group member can jump in for an hour and find the base exactly where it was left. You do not have to be playing for the world to stay up, unlike a hosted session, but the machine running it does have to stay powered on.
The App ID trap (read this first)
This is the single most common point of confusion, and it shows up on the forums constantly: a player launches what they think is the game and instead gets a console window talking about a "dedicated server" with no way to actually play. The cause is that the game and the server are two different Steam entries:
| What it is | Steam App ID | Notes |
|---|---|---|
| Abiotic Factor (the game you play) | 427410 | Launch this to play; never use it for headless hosting |
| Abiotic Factor Dedicated Server (the host tool) | 2857200 | Headless, no playable view; this is what you install via SteamCMD |
Install the server with SteamCMD
SteamCMD downloads the server tool anonymously, no Steam account needed:
# Linux example
steamcmd +@sSteamCmdForcePlatformType windows \
+login anonymous \
+force_install_dir ~/abioticserver \
+app_update 2857200 validate \
+quitThe server binary installs to AbioticFactor/Binaries/Win64/AbioticFactorServer-Win64-Shipping.exe. On Linux this runs through Proton or the provided wrapper; on Windows you run the executable directly.
Launch parameters and player cap
A typical launch line looks like this:
AbioticFactorServer-Win64-Shipping.exe -log -newconsole \
-useperfthreads -NoAsyncLoadingThread \
-MaxServerPlayers=6 -Port=7777 -QueryPort=27015 \
-SteamServerName="My Facility" -ServerPassword=- -MaxServerPlayers sets the cap. The developers balance around 6. You can raise it toward 24, but everything above 6 is community-supported and can hurt stability and resource balance.
- Do not add -NOSTEAM. It breaks server discovery and connections.
Sandbox settings location
If your SandboxSettings.ini seems to be missing, it is because the server generates it on first successful launch, per world. Look in:
Saved/SaveGames/Server/Worlds/<worldName>/SandboxSettings.iniStart the server once, let it create the world, stop it, then edit that file. A config that "is not there" is almost always a server that has not completed a clean first boot yet.
Ports to open
| Port | Protocol | Purpose |
|---|---|---|
| 7777 | UDP | Game traffic |
| 27015 | UDP | Steam query / server browser |
If you change the game port with -Port, forward the matching port. A server that starts fine locally but no one can connect to is almost always a port-forwarding or firewall gap.
Which should you pick?
- Pick an online session if you and your friends always play at the same time, want zero setup, and do not mind the world closing when the host logs off.
- Pick a dedicated server if your group is spread across schedules or time zones, wants drop-in play, or wants a base that keeps growing while people are away. This is the most-requested setup on the forums for exactly that reason.
The middle road is self-hosting a dedicated server on a spare PC: free, but the machine must stay on, you handle updates and crashes, and a home connection plus consumer hardware can struggle once you push past 6 players. Many groups try this, hit the always-on requirement, and move to a managed host.
Want the persistent world without babysitting a PC? Host an Abiotic Factor server with Supercraft from $5.99/mo. The facility stays online 24/7, crossplay works out of the box, updates and daily backups are handled, and you pick from 5 regions for low ping. Running a different survival world too? Supercraft also hosts a managed Valheim dedicated server with the same always-on uptime.