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Unstable SMP SimulatorMinecraft modpack for 1.21.11

All of the Minecraft Simulators (Unstable, Bliss, Manhunt etc) you'll ever need with new Sims automatically updated without needing to change the modpack

client and servernewest supported release 1.21.11TechnologyAdventureOptimizationChallenging
Latest version
1.21.11-6.0
Minecraft
1.21 to 1.21.11
Java
Java 21+
Loader
Fabric
Licence
LicenseRef-All-Rights-Reserved
Downloads
139.8k
Updated
17 d ago
Available on
Modrinth
Space NodeOur hosting

Host Unstable SMP Simulator servers

One click and Unstable SMP Simulator is installed with the right loader, on hardware built for it.

  • 1.21.11
  • Fabric
  • One click modpack install
  • Dependencies handled
  • Tuned startup flags
  • NVMe SSD
Deploy a serverFrom €0.90 per GB

Minecraft versions

Every version Unstable SMP Simulator declares support for, newest first, with the Java runtime that version needs.

Other modpacks
MinecraftThroughJavaEvidenceReleased
1.21.11Fabric21+declared9 Dec 2025
1.21Fabric21+declared13 Jun 2024

Download

From Unstable SMP Simulator’s own host. Nothing is re-hosted here.

Browse 33 indexed releases

Most recently published release

1.21.11-6.0release21 Oct 2026

unstable-1.21.11.mrpack · 0.4 MB · for 1.21.11 · Fabric

Download this release
3dcd96669cb5…
Older versions24
  • 1.21-5.021 Oct 20261.211.7 MB3c6554542d0a…Get
  • 1.21.11-5.019 Oct 20261.21.11301.7 MB9e1464a9b5af…Get
  • Vex-1.21.11-7.4.110 Oct 20261.21.11261.2 MB4aa4f46cbe58…Get
  • Vex-1.21.11-7.410 Oct 20261.21.11261.2 MB228b93153773…Get
  • 1.21-4.110 Oct 20261.21459.9 MB130920df0b6b…Get
  • 1.21-4.030 Sept 20261.21398.4 MB369b2566e20f…Get
  • Vex-1.21.11-7.310 Sept 20261.21.11264.1 MB674a5b8dabf9…Get
  • Vex-1.21.11-7.29 Sept 20261.21.11263.7 MBcf00d3b5cf34…Get
  • Vex-1.21.11-7.18 Sept 20261.21.11261.0 MB203002722cad…Get
  • Vex-1.21.11-7.07 Sept 20261.21.11261.0 MB10a9956c8160…Get
  • 1.21.11-4.010 Aug 20261.21.11470.5 MB03186096619b…Get
  • Vex-1.21.11-6.226 Jul 20261.21.11483.7 MB4.0k downloadsb269144a269e…Get
  • Vex-1.21.11-6.123 Jul 20261.21.11473.1 MB2.8k downloads349de5c9c3e5…Get
  • Vex-1.21.11-6.023 Jul 20261.21.11464.7 MB243 downloads96a9ba0648b7…Get
  • Vex-1.21.11-5.023 Jul 20261.21.11499.3 MB69 downloadsa4f5abb6fa0b…Get
  • Vex-1.21.11-4.022 Jul 20261.21.11451.6 MB1.0k downloadscd95b0721cf8…Get
  • Vex-1.21.11-3.019 Jul 20261.21.11293.1 MB2.1k downloadsf988b1297322…Get
  • Vex-1.21.11-2.018 Jul 20261.21.11286.6 MB412 downloads2d1339d123c9…Get
  • Vex-1.21.11-1.115 Jul 20261.21.11223.0 MB1.8k downloadsd78ad684b0a8…Get
  • Vex-1.21.11-1.015 Jul 20261.21.11222.4 MB397 downloads7570371dbf88…Get
  • 1.21.11-3.124 Jun 20261.21.11161.0 MB8.5k downloads312a1126e13e…Get
  • 1.21-3.020 Jun 20261.21384.3 MB3.2k downloads7d7bbf7de003…Get
  • 1.21.11-3.020 Jun 20261.21.11489.1 MB830 downloadsfe212c887e65…Get
  • 1.21.11-2.412 Jun 20261.21.11343.2 MB2.5k downloads22b15aa3a74b…Get

Frequently asked

Does Unstable SMP Simulator work on Minecraft 1.21.11?

Yes. 1.21.11 is the newest Minecraft version Unstable SMP Simulator declares support for, and the claim comes from the author's own release metadata rather than from a compatibility list somebody maintains by hand.

Which Minecraft versions does Unstable SMP Simulator support?

Everything the author has declared, from 1.21 up to 1.21.11. The full list is in the table above, with the Java runtime each version needs next to it.

Do I need to install Unstable SMP Simulator on the client or the server?

Both. Every player needs it installed and so does the server, so anyone joining without it will be refused.

Which platform or loader does Unstable SMP Simulator support?

Fabric. A build for one platform or loader will not necessarily load on another, so this is the first thing to check before the Minecraft version.

Which Java version do I need for Unstable SMP Simulator?

Among the supported Minecraft releases above, the highest recorded requirement is Java 21 or newer. Use the requirement for the exact Minecraft version you run; previews and snapshots may differ.

What licence is Unstable SMP Simulator under?

LicenseRef-All-Rights-Reserved, as stated by the author on the platform we synced it from. Check the project's own page before redistributing or bundling it.

How do I install Unstable SMP Simulator?

Use a launcher that imports packs, such as Prism Launcher, the Modrinth App or the CurseForge app, and open the pack file with it. The launcher installs the right loader and mods for you; installing a pack's mods by hand is the error-prone way.

Where do I download Unstable SMP Simulator safely?

Start with the author's page on Modrinth, which is where the data here is synced from. MCReference does not host or repackage files. When available, recorded download links go to the source for that release; verify the publisher, filename and any available checksum before running it.

Works on the same versions

Ordered by how much of the recent Minecraft version coverage overlaps, not by popularity.

MAX FPS: Optimized🚀 MAX FPS WITHOUT UNNECESSARY MODS! Only 16 optimization mods - NOTHING EXTRA! ✅ ALL MAJOR VERSIONS ⚡ INSTALLS ON ANY LAUNCHER! (Guide below)Simply Optimized ReloadedAn unofficial port of Simply Optimized built to support every major mod loader and stay current with the newest versions of Minecraft.PacktrixPre-packed Official Modpack containing Patrix Resource Pack for easy install using Fabric/Quilt.FPS+ PvP Boost | Ultimate FPS & Combat Client [ Every Version ]Ultra-lightweight FPS boost & PvP modpack for Fabric. Boost FPS on low-end PCs with Sodium optimizations, lower input lag, cleaner visuals, and combat HUD tweaks built for Hypixel Bedwars, Duels, PotPvP & CPVP. Maximize frames and dominate fights.ElixirA well-researched performance & optimization modpack to make the game run smoother! With shader & Fresh Animations support. 26.3 ✔Uton OptimizatorEffective optimization for weak PCs and even for mobile devices.

Details from Modrinth, where the author last updated it on 21 Oct 2026. We do not host files or republish descriptions. Available download links point to the author’s own release.

Is this information wrong or missing something? .