Icarus dedicated server setup and prospects

An Icarus dedicated server is a free Windows program (Steam app 2089300, anonymous download, IcarusServer.exe) configured through Icarus/Saved/Config/WindowsServer/ServerSettings.ini and a handful of launch arguments. It listens on UDP 17777 for the game and UDP 27015 for the Steam query, holds up to eight players, and runs one prospect at a time - a mission or an open-world map - which it creates, loads or resumes according to the settings. Two defaults catch nearly everyone: the server shuts itself down if nobody joins within 300 seconds of starting, and again 300 seconds after the last player leaves. On a host that is meant to stay up, set ShutdownIfNotJoinedFor and ShutdownIfEmptyFor to a negative value before anything else.

How Icarus servers and prospects work#

Icarus is built around prospects. A prospect is one drop to the planet: a map, a difficulty, a mission set, and a save file that holds the world state. There are two kinds:

• Mission prospects: a limited-time drop with objectives. Players complete them and return to orbit; the prospect ends.
• Open World and Outpost prospects: persistent maps with no mission timer, meant for long-running bases. Open World is what most dedicated servers run.

A dedicated server hosts one prospect at a time. Between prospects it sits in a lobby state, where players or admins choose what to load next. That lobby is why the server has settings about who may launch and delete prospects, and why the default shutdown timers exist: the server was designed to be spun up for a session and stopped afterwards.

What stays with the player: characters, their talents, the orbital workshop and blueprints are tied to the player's account and travel between prospects. What stays with the server: the prospect save, with everything built and stored in it.

Missions or open world on a dedicated server

Both kinds of prospect run on a dedicated server, but they suit it differently.

Mission prospects are short by design. A group drops, completes a contract over a few sessions, and extracts. On a dedicated server that works, but the server spends a lot of its life in the lobby between missions, and somebody has to choose and launch the next one. That is where AllowNonAdminsToLaunchProspects matters: in a trusted group, letting anyone launch the next mission saves waiting for the admin; in a public group, it lets a stranger end a mission halfway through.

Open-world prospects are what a dedicated server is best at. There is no timer and no extraction deadline, bases can grow for weeks, and players log in and out on their own schedules while the world waits for them. Most groups who rent a server do it for exactly this, and run a single open-world prospect until they lose interest or a major update suggests a fresh start.

A middle path is common too: an open-world prospect as the group's permanent home, with mission prospects run occasionally on a second server or from the lobby when everyone is online for an evening. Because characters and their progression belong to the players rather than the prospect, moving between the two costs nothing except time.

Whichever you choose, settle difficulty and hardcore before creating the prospect. Both are fixed at creation; changing them means starting again.

Requirements and resource usage#

Icarus uses Unreal Engine 4 and a large map, so the server is not light. Memory grows with the size of bases and the number of placed objects in the prospect, and the open-world maps are heavier than short missions.

• CPU: the game thread and AI. Clock speed matters for smooth combat and building.
• Disk: the install is large - plan for 30 GB or more - and prospect saves grow with bases. Keep room for backups.
• Players: the cap is 8, so sizing is about how big the world gets rather than how many people join.

These are typical numbers from community servers, not official minimums. Watch memory after a week on an open-world prospect before deciding; CPU vs RAM for game servers explains how to tell which one is limiting you.

Installing and first start#

The server is Windows-only:

$ steamcmd +force_install_dir C:\icarus-server +login anonymous +app_update 2089300 validate +quit$ cd C:\icarus-server$ IcarusServer.exe -log -SteamServerName="Arctic Prospectors" -PORT=17777 -QueryPort=27015

-log is not optional in practice: without it, the console shows nothing while the server runs. On Linux the server runs under Wine, which is how many hosts and container images run it; it works, but it is not supported, and updates occasionally break it. SteamCMD explained covers anonymous installs and updating.

The first start creates ServerSettings.ini. When you run the server yourself, the default location is under %LOCALAPPDATA%\Icarus\Saved\Config\WindowsServer\; with -UserDir you can put the whole saved data folder somewhere else, which makes backups and moves simpler. Stop the server, edit the file, start again.

Launch arguments

Use -SteamServerName for the name rather than SessionName in the ini. The official notes say the ini setting does not currently work for this.

ServerSettings.ini, key by key#

Every setting lives in one section:

[/Script/Icarus.DedicatedServerSettings]SessionName=JoinPassword=long-join-passwordMaxPlayers=8AdminPassword=a-different-long-passwordShutdownIfNotJoinedFor=-1.000000ShutdownIfEmptyFor=-1.000000AllowNonAdminsToLaunchProspects=FalseAllowNonAdminsToDeleteProspects=FalseLoadProspect=CreateProspect=ResumeProspect=TrueLastProspectName=

The shutdown timers deserve one more sentence. With the defaults, a server on a panel looks broken: it starts, nobody joins in five minutes, and it stops. If your host restarts it automatically, it loops; if not, it sits offline. -1 on both turns the server into a normal always-on server.

AllowNonAdminsToLaunchProspects is True by default, which on a public server means any visitor can end your open-world prospect and launch another. For anything but a trusted private group, set it to False.

Creating, loading and resuming prospects#

Three settings decide what the server runs when it starts: CreateProspect makes a new prospect, LoadProspect loads a named one, and ResumeProspect picks up the last one the server ran. Set only one of them at a time, and the behaviour is predictable.

CreateProspect takes four values separated by spaces:

CreateProspect=<ProspectType> <Difficulty 1-4> <Hardcore True/False> <SaveName>

For example, from the official documentation:

CreateProspect=Tier1_Forest_Recon_0 3 false TestProspect01

The four values, in order:

• ProspectType is the internal name, not the display name. The official dedicated server wiki keeps a list; open-world maps have names such as OpenWorld_Styx and Outpost006_Olympus.
• Difficulty runs from 1 (easy) to 4 (extreme).
• Hardcore true turns on the game's hardcore rules for that prospect, where dying costs far more than usual.
• SaveName is the file name the prospect is saved under, and the name you use later with LoadProspect.

The usual pattern for a long-running open-world server is:

1. Set CreateProspect with the open-world map, difficulty and a save name. Start the server once.
2. Stop it, clear CreateProspect, and leave ResumeProspect=True.
3. From then on, every start resumes the same prospect.

Leaving CreateProspect set after the first start is a common mistake: depending on the version, the server either recreates the prospect or complains that it exists. Clear it once the prospect is made.

Prospect saves are JSON files in the server's Saved/PlayerData/DedicatedServer/Prospects folder. To move a prospect you played locally onto the server, copy its file from your local Prospects folder into that one with the server stopped, then load it by name.

Ports and connecting#

Both must be open and both are UDP. If your host gives you different numbers, pass them with -PORT and -QueryPort. Game server ports explained covers why a server can show in the browser but refuse connections when only one is reachable.

Players find the server in the in-game dedicated server browser by name. Search for a distinctive word in your server name, because the list is long. When the server is in its lobby, joined players see the prospect selection; when a prospect is running, they drop straight in.

Admin commands#

Admin access is a password. In chat, a player types /AdminLogin followed by the AdminPassword value, and the server grants admin for that session. The commands that follow:

In the lobby, the same console accepts LoadProspect, CreateProspect and ResumeProspect with the arguments described above, so an admin can switch prospects without editing files.

Use /ReturnToLobby carefully on an open-world server: it ends the running session for everyone. Announce it first with /AdminSay. And because admin is a single shared password, change it whenever someone who knows it leaves the group - server rules, moderation and staff covers handling staff on small servers.

Saves, backups and updates#

The prospect file is the world. Everything placed, built and stored in that prospect is in one JSON file, which makes backups simple and corruption total: if that file is damaged, the whole prospect is.

• Stop the server cleanly before copying the prospect. A kill can lose everything since the last save.
• Back up before every update. Icarus patches often, and large updates have changed prospect content.
• Keep copies off the machine. A copy beside the original protects against nothing that matters. Backups that actually restore explains why restoring one occasionally is the real test.

Update the server through SteamCMD whenever the game updates; clients on a newer version cannot join an older server. A weekly scheduled restart keeps memory steady on long-running open-world prospects - see restart schedules that help.

Keeping a long-running prospect healthy

An open-world prospect that has run for months is a large save with a lot of structures, storage and deployables in it, and it costs more than a fresh one to load and to run. A few habits help:

• Watch the save size. A prospect file that keeps growing quickly usually means someone is building on a scale the server will feel - very large bases, mass storage, or farms of deployables. It is not a problem by itself, but it explains a slow load after a restart.
• Restart on a schedule. Memory tends to creep on Unreal Engine servers that run for days. A restart at a quiet hour, after a clean save, resets it.
• Clear what nobody uses. Abandoned outposts and half-built bases from players who left still cost the server. Agree as a group when it is fine to dismantle them.
• Save before risky events. Boss fights, big storms and large construction projects are the moments a crash costs the most. A manual backup before them is cheap insurance.

None of these needs a setting. They are the routine that keeps a server pleasant after the novelty of a new world has worn off.

On RE:NODE, backup slots on every game plan are stored off the machine, can be locked against rotation and restore with a button, and the Schedules tab can take a backup before a restart. Icarus's server is Windows-only and is not in the catalogue, so treat this as a description of the panel rather than an Icarus plan.

Troubleshooting#

The server stops by itself after five minutes. The shutdown timers. Set ShutdownIfNotJoinedFor and ShutdownIfEmptyFor to -1.

The server shows the wrong name. SessionName in the ini is not honoured. Use -SteamServerName on the command line.

A visitor ended our open-world prospect. AllowNonAdminsToLaunchProspects is still True. Set it to False and restore the prospect from a backup if needed.

A new prospect appeared instead of ours. CreateProspect was still set, or LoadProspect named a file that does not exist. Clear CreateProspect and check the save name.

Nobody can connect. Check both UDP ports and that the server is updated to the current game version. Why your game server keeps restarting covers crash loops if the server keeps falling over.

FAQ#

How many players can join an Icarus dedicated server?

Eight. MaxPlayers accepts 1-8, and the game is balanced around groups of that size.

Can a dedicated server run an open-world prospect permanently?

Yes. Create the open-world prospect once with CreateProspect, then leave ResumeProspect=True and turn off the shutdown timers. The server resumes it on every start.

Why does my Icarus server keep shutting down?

The default timers stop the server after 300 seconds without a player joining, and 300 seconds after the last player leaves. Set both to a negative value for an always-on server.

Can I bring a prospect from my own game to the server?

Yes. Copy the prospect's JSON file from your local Prospects folder into the server's Saved/PlayerData/DedicatedServer/Prospects folder with the server stopped, then load it by name.

Does the Icarus server run on Linux?

Only under Wine. Many hosts do it successfully, but it is not supported, and updates sometimes break it until the Wine setup is updated.