---
title: "Icarus Server Settings Explained"
description: "Every line in Icarus ServerSettings.ini, plus the Custom World Settings that live in the prospect file rather than the config."
url: "https://www.gameserverkings.com/knowledge-base/icarus/icarus-server-settings/"
category: "Icarus"
category_url: "https://www.gameserverkings.com/knowledge-base/icarus/"
published: "2026-09-12T06:30:33.830Z"
updated: "2026-09-12T06:32:35.847Z"
source_format: "markdown"
site: "GameServerKings"
---

# Icarus Server Settings Explained

Short answer: Icarus has **twelve** settings in `ServerSettings.ini` and a separate in-game **Custom World Settings** menu. The two are not the same system — the `.ini` configures the *server*, and Custom World Settings are saved into the *prospect file*. Below is every option in both, with the defaults RocketWerkz ship.

> [!NOTE] Checked against Icarus **3.0.27.157242-rel-DangerousHorizons**
> Week 249, released 10 September 2026. The `ServerSettings.ini` reference is RocketWerkz's own, last revised June 2024; Custom World Settings arrived in Week 211, December 2025.

## The whole file

This is the complete template RocketWerkz publish, unedited:

```ini
[/Script/Icarus.DedicatedServerSettings]
SessionName=
JoinPassword=
MaxPlayers=
AdminPassword=
ShutdownIfNotJoinedFor=300.000000
ShutdownIfEmptyFor=300.000000
AllowNonAdminsToLaunchProspects=True
AllowNonAdminsToDeleteProspects=False
LoadProspect=
CreateProspect=
ResumeProspect=True
LastProspectName=
```

It does not exist until the server has booted once. RocketWerkz: *"the settings file gets generated on first prospect/lobby"*. Start the server, let it reach the lobby, then edit `Icarus/Saved/Config/WindowsServer/ServerSettings.ini`.

## Every option

| Setting | Default | What it does |
|---|---|---|
| `SessionName` | empty | **Does nothing.** See the warning below |
| `JoinPassword` | empty | Password required to join. Empty means open |
| `MaxPlayers` | empty | Concurrent player cap. RocketWerkz document minimum 1, maximum 8 |
| `AdminPassword` | empty | Password for `/AdminLogin`. Empty is dangerous — see below |
| `ShutdownIfNotJoinedFor` | `300` | Seconds to wait after boot for a first player before returning to lobby |
| `ShutdownIfEmptyFor` | `300` | Seconds to wait after the last player leaves before returning to lobby |
| `AllowNonAdminsToLaunchProspects` | `True` | Whether anyone in the lobby can create or load a world |
| `AllowNonAdminsToDeleteProspects` | `False` | Whether anyone in the lobby can delete a world |
| `LoadProspect` | empty | Prospect save name to load at start-up |
| `CreateProspect` | empty | Create and launch a new world at start-up |
| `ResumeProspect` | `True` | Resume whatever `LastProspectName` points at |
| `LastProspectName` | empty | Written by the server; used by `ResumeProspect` |

> [!WARNING] `SessionName` is a trap
> RocketWerkz's own note on it reads: *"This setting currently does nothing, use the -SteamServerName commandline"*. Editing `SessionName` and restarting produces no visible change, which reads exactly like a broken server. On a [hosted Icarus server](/games/icarus/) the `SERVER_NAME` variable in your panel is what feeds `-SteamServerName`, so set the name there and leave `SessionName` blank.

### The two shutdown timers

These are the most misread settings in the file, because "shutdown" does not mean the process exits — it means the prospect unloads and the server returns to its lobby. Both behave the same way:

- **Below 0** — run indefinitely. This is what a persistent Open World server wants.
- **Exactly 0** — return to lobby as soon as possible.
- **Above 0** — wait that many seconds.

RocketWerkz add that during the wait window *"the game will be paused"*, and caution: *"Only use low values if you want to use the lobby to start prospects each time."*

### The passwords

`AdminPassword` ships empty, and empty is not the same as disabled. RocketWerkz spell out the consequence: *"If left empty just using the RCON /AdminLogin will give admin privilege's to a player (effectively an empty password)."* Any player who joins can then claim admin. Set it before the server is reachable. The commands it unlocks are covered in [Icarus Console Commands: What Actually Works](/knowledge-base/icarus/icarus-console-commands/).

### The player cap

RocketWerkz's config reference documents `MaxPlayers` as *"Max Players that can be on the server at once. Minimum 1, Maximum 8"*, and the Icarus Steam store page still describes the game as being for *"up to eight co-op players"*.

There is a wrinkle. In the Week 54 update of 16 December 2022, RocketWerkz wrote that *"Dedicated Servers will be opened up to more than 8 players, but at the risk of server degradation as this session count fluctuates"* — while peer-to-peer sessions stayed capped at 8. The documented, supported value is still 1–8, and that is what we would build a server around. Treat anything above it as untested rather than as a feature.

## Launch parameters

Some things are not in the `.ini` at all. RocketWerkz's command-line arguments:

| Parameter | Purpose |
|---|---|
| `-SteamServerName=` | The name in the server browser, up to 64 characters |
| `-PORT=` | Game port (default `17777`) |
| `-QueryPort=` | Steam query port (default `27015`) |
| `-MULTIHOME=` | Bind to a specific IP |
| `-UserDir=` | Move the `Saved/` directory elsewhere |
| `-saveddirsuffix=` | Suffix the `Saved/` folder, e.g. `Saved_player2/` |
| `-LOG=` | Log path relative to `Saved/Logs/` |
| `-ABSLOG=` | Absolute log path |
| `-ResumeProspect` | Resume the last world at start-up |
| `-LoadProspect=[Name]` | Load a named world at start-up |
| `-CreateProspect="[Type] [Difficulty] [Hardcore] [SaveName]"` | Create a world at start-up |

On a hosted server the first three are already wired to your panel variables and your allocated ports; the rest are set in the start-up command.

## Custom World Settings

This is the newer system and the one most "Icarus server settings" pages have not caught up with. RocketWerkz unlocked the Custom World Settings menu in the **Week 211 update, 19 December 2025**, initially with a single toggle:

> *"Arachnophobia Mode, which allows you to toggle spider spawning on or off."*

They added a second in the **Week 223 update, 13 March 2026** — "Mount Unclaim Requires Ownership", which stops other players unclaiming a tame that is not theirs — and described the access model at the same time:

> *"This setting, like other Custom World Settings, can be toggled by the host player if hosting locally, or by anyone logged in as admin on a dedicated server."*

Three things follow from that, and they matter:

1. **They are per-world, not per-server.** Custom World Settings are written into the prospect file, so they travel with the save and have to be set again on a new world.
2. **They need an admin login.** On a dedicated server, `/AdminLogin` first, then the menu.
3. **They can be changed mid-prospect**, from the escape menu, without a restart.

Defaults are asymmetric on purpose. RocketWerkz: *"For new Prospects, Arachnophobia Mode will default to Off. However, for existing Prospects, it will default to On"* — so an established world does not silently gain spiders.

> [!NOTE] Set them from in-game, not from the lobby
> In the hotfix accompanying Week 211, RocketWerkz logged a known issue where the Custom World Settings button could fail when creating a prospect from the dedicated server lobby, with the workaround being *"to change the setting as an admin while in game using the button in the escape menu"*. The in-game route has been the dependable one since.

## Common Questions

### Why did my server name not change?

Because you edited `SessionName`, which RocketWerkz confirm does nothing. The name comes from `-SteamServerName`, which on a hosted server is the `SERVER_NAME` variable.

### How do I stop my server returning to the lobby?

Set both `ShutdownIfNotJoinedFor` and `ShutdownIfEmptyFor` to a negative value. Anything below zero runs indefinitely.

### Are there difficulty settings in ServerSettings.ini?

No. Difficulty is chosen when the prospect is created — a value of 1 to 4, passed to `CreateProspect` or picked in the lobby UI — and it is fixed for the life of that world.

### Can I edit settings while the server is running?

`ServerSettings.ini` is read at start-up, so those need a restart. Custom World Settings are live and change from the escape menu.

### Where does the ban list live?

Bans made with `/BanPlayer` are written to a saved ban list under the server's `Saved` folder and persist across restarts. `/UnbanPlayer` is the supported way to reverse one.

## What to Read Next

- [Icarus Console Commands: What Actually Works](/knowledge-base/icarus/icarus-console-commands/) — the admin commands these settings gate
- [How to Set Up an Icarus Dedicated Server](/knowledge-base/icarus/icarus-dedicated-server-setup/) — install, ports and first boot
- [Icarus Prospects on a Dedicated Server](/knowledge-base/icarus/icarus-prospects-explained/) — why one server runs one world
- [How to Play Icarus With Friends](/knowledge-base/icarus/icarus-multiplayer-with-friends/) — joining and player limits

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