---
title: "How to make an RLCraft server"
description: "The most downloaded pack, and the harshest: what thirst, temperature and skill-gated progression change when you play as a group."
url: https://tickserv.com/en/guides/rlcraft
site: "TickServ (https://tickserv.com)"
lang: en
published: 2026-08-22
games: [minecraft]
---
# How to make an RLCraft server

RLCraft is the most downloaded modpack there is: **nearly 30 million downloads** on CurseForge. Its promise is simple — make Minecraft "unfairly difficult" — and its consequences on a server are less so. Here's what actually changes when you host it for a group.

## What RLCraft does to the game, and why that matters in multiplayer

This isn't a pack that adds machines: it's a pack that removes safety nets. Its authors describe it as an "incredibly hardcore and semi-realism challenge revolving around survival, RPG elements, and adventure-like exploration":

- **thirst and temperature** — two more gauges to watch, constantly;
- **food no longer heals** — passive regeneration is switched off;
- **progression is gated by skills**: you can't use a piece of equipment before unlocking it;
- **heavily reworked mobs and dungeons**, including dragons and aggressive wildlife that prowls at night.

Solo, dying often is part of the deal. **In a group, it changes the server's dynamic**: nobody "catches up" in one evening, and a player joining three weeks in starts a very long way back. That's the one real piece of group advice for this pack: start together, or accept that newcomers are playing a different game.

## Version and Java: RLCraft lives on 1.12.2

RLCraft targets **Minecraft 1.12.2** (and 1.11.2) on the **Forge** loader. That isn't an archival detail: it's a generation of Minecraft older than most modern packs, with its own requirements.

The Java version is tied to the Minecraft version — the [Minecraft Wiki](https://minecraft.wiki/w/Server/Requirements) asks for Java 17 from 1.18 and Java 21 from 1.20.5, and "a Java runtime (JRE), version 8 or higher" for earlier versions like this one. If you're self-hosting, that's the first trap: a Java picked at random won't start a pack of this generation.

Here, you choose nothing: the loader and the Java version are derived from the pack.

## RAM: its authors give the figure, and it's about the heap

RLCraft is one of the few packs to state its need plainly. Its page recommends **"allocating 3 to 4GB's of RAM"**, with example arguments showing `-Xmx4G`.

But `-Xmx` is the **JVM heap** — not the machine's memory. The operating system, Docker and Java's off-heap memory live beside it. Here, the heap is the smaller of "RAM − 2 GB" and "75% of RAM":

| Tier you pick | Actual JVM heap | Verdict for RLCraft            |
| ------------- | --------------- | ------------------------------ |
| 4 GB          | 2 GB            | below the stated 3–4 GB        |
| **8 GB**      | **6 GB**        | **the right choice**           |
| 16 GB         | 12 GB           | large group, distant exploring |

In other words: **take the 8 GB tier.** The 4 GB tier yields only a 2 GB heap, less than the pack asks for itself — and the creation screen will warn you, because it compares heaps, not machine sizes.

## CPU, for a reason specific to this pack

RLCraft fills the world with creatures: dragons, giant insects, nocturnal wildlife. Every living entity has to be simulated twenty times a second, and a base under attack at night can concentrate a great many in one place.

The symptom is recognisable: the server doesn't fall over, it **drags** — hits land late, mobs teleport. If the heap is comfortable and it happens anyway, it's the processor: the **dedicated CPU** level is the only change that answers it.

Conversely, a server that **dies** when a player wanders away from spawn is a heap problem, not a CPU one: generating chunks is the most memory-hungry thing it does.

## The settings that genuinely matter here

On a pack this punishing, two settings change the experience more than all the others:

- **Simulation distance** (3 to 32, default 10): the radius in which the server keeps the world — and therefore the mobs — alive. Dropping it to **6 or 8** is the cheapest fix for lag, and on RLCraft it has a visible effect, because there's a great deal to simulate.
- **The whitelist**: RLCraft attracts the curious, and an open server on a weeks-long hardcore run is a bad idea. Add your group's usernames.

PvP deserves an explicit decision before you start, too: on a pack where dying is expensive, it isn't something you switch on "to see".

## The first boot, and your saves

Expect **15 to 25 minutes** on first boot: downloading the pack, resolving mods, then generating a world stuffed with added structures. Later boots are quick. Don't kill it thinking it failed — that's the most common phantom failure on big packs.

After that, the world is archived **before every shutdown**, with a `save-all flush` immediately before, and restored on the next boot. An automatic backup runs **every 30 minutes** while you play, of which the **last 5** are kept.

On RLCraft that last line matters more than elsewhere: a run represents dozens of hours of skill-gated progression, and it doesn't get redone over a weekend.

## What not to do

**Switch packs on an RLCraft world.** The world holds thousands of blocks and entities Minecraft has never heard of; loaded without its mods, it loses them permanently. To try something else, create a second server.

**Move up a major version.** RLCraft is a 1.12.2 pack; there's no upgrade path to a newer generation that preserves the run.

> [Create your Minecraft server](https://tickserv.com/en/games/minecraft) and pick RLCraft from the modpack list. Your first session is free.