Deploy & Play

Deploy your instance and launch Minecraft — understand what "deploy" means and how launching works.

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Deploying Your Instance

Before Minecraft can run, Polymerium needs to deploy your instance. This is the step where your metadata (version, loader, mod list) gets turned into an actual, runnable game directory.

Click Deploy — or just click Launch and Polymerium will deploy automatically if needed.

What Deploy Does

Downloads all required files — Minecraft jars, loader libraries, and mods — to the shared cache
Builds the game directory using symbolic links pointing into the cache
Generates launch parameters (classpath, JVM args, etc.)

First Deploy vs. Incremental Deploys

Your first deploy downloads everything from scratch — expect it to take as long as installing a fresh modpack on any launcher. Polymerium uses an aggressive, optimized download strategy, so on a good network it can be faster than other launchers.

The real speed advantage comes on subsequent deploys. When you make small changes (add a mod, switch a loader version), Polymerium only downloads what's new or changed and rebuilds the game directory with symlinks. Incremental deploys are fast — often near-instant.

Fast Mode

If nothing has changed since your last deploy (same mods, same versions, same settings), Polymerium skips the deploy entirely and goes straight to launch. This makes subsequent launches feel instant.

Launching

Click Launch to start Minecraft. Polymerium supports three launch modes:

Mode	What It Does
Managed (default)	Polymerium tracks the game process, captures output, and detects crashes. Recommended.
Fire-and-forget	Launches the game and detaches. Use this if you want to close Polymerium while playing.
Debug	Exports the full launch command for troubleshooting. Doesn't actually start the game.

First Launch Checklist

What's Next?

You're playing! Here's where to go from here:

Understand what just happened — read Core Concepts to learn why Polymerium works this way
Manage your instances — accounts, snapshots, tags
Go deeper — deployment rules, CLI, modpack development