Introduction to Slay the Spire Modding

Slay the Spire, a popular roguelike deck-builder, offers a vibrant modding community that significantly enhances gameplay and replayability. As of 2025 and into 2026, modding methods are well-established for the original game and are evolving for its successor, Slay the Spire 2, which entered early access in 2025. This guide will detail the processes for both versions, emphasizing the tools and steps required to introduce custom content to your game.

Modding the Original Slay the Spire (STS1)

For the original Slay the Spire, the primary method for installing and managing mods in 2025 largely centers around two foundational tools: ModTheSpire and BaseMod. These tools act as the mod loader and a base library that most other mods rely on.

Required Tools for STS1 Modding

To begin modding the original Slay the Spire, you will need the following core components:

ModTheSpire: This is the essential mod loader for Slay the Spire. Without it, other mods cannot be loaded.

BaseMod: This mod serves as a foundational library that many other mods depend on to function correctly. It doesn't add playable content itself but provides necessary hooks and functionalities for other mods.

StSLib (Optional but Recommended): Similar to BaseMod, StSLib is another common dependency for many mods, providing additional functionalities for mod creators.

Installing STS1 Mods via Steam Workshop (Recommended)

The easiest and most recommended method for installing mods for the Steam version of Slay the Spire is through the Steam Workshop.

1. Navigate to the Slay the Spire Workshop: From your Steam homepage, open the Slay the Spire game page and click on 'Workshop'. 2. Subscribe to Core Mods: Search for and subscribe to 'ModTheSpire' and 'BaseMod'. Many mods also require 'StSLib', so it's advisable to subscribe to that as well. Subscribing automatically downloads and keeps these mods updated. 3. Subscribe to Desired Mods: Browse the Workshop for other mods that interest you and click 'Subscribe' for each one. The Workshop page for individual mods will often list their requirements, so ensure you subscribe to any necessary dependencies.

Manual Installation of STS1 Mods

If you are using a non-Steam version of the game or a mod is not available on the Workshop, you can install mods manually.

1. Locate Game Directory: Find your Slay the Spire installation folder. On Windows, this is typically C:\Program Files (x86)\Steam\steamapps\common\SlayTheSpire for Steam users. 2. Download ModTheSpire and BaseMod: Obtain the latest .jar files for ModTheSpire and BaseMod from their respective GitHub release pages. Note that the GitHub version of ModTheSpire may be out of date compared to the Steam Workshop version, so the Workshop is generally preferred for compatibility and updates. 3. Copy ModTheSpire: Copy the ModTheSpire.jar file, along with MTS.cmd (for Windows) or MTS.sh (for Linux), directly into your Slay the Spire install directory. 4. Create a 'mods' Folder: Inside your Slay the Spire install directory, create a new folder named mods. 5. Place Mod Files: Download the .jar files for BaseMod and any other desired mods and place them into the newly created mods folder. Ensure you don't have duplicate installations of the same mod from different sources (e.g., both Workshop and manual) to avoid conflicts.

Launching Slay the Spire with Mods (STS1)

After installing your mods, the process to launch the game with them is straightforward:

1. Launch from Steam: When you click 'Play' for Slay the Spire in Steam, you will be presented with an option to 'Play with Mods'. Select this option. 2. ModTheSpire Launcher: A ModTheSpire popup window will appear, listing all your downloaded or subscribed mods. 3. Enable Mods: Check the boxes next to the mods you wish to use for your current run. New mods are often disabled by default on their first run. 4. Click 'Play': Press the 'Play' button within the ModTheSpire launcher to start the game with your selected mods active. You will see a new 'Mods' button on the game's homepage, providing information on enabled mods.

Modding Slay the Spire 2 (STS2) - Early Access

Slay the Spire 2 was announced to enter early access in 2025, and early modding guides for it emerged in March-April 2026. STS2 utilizes the Godot 4.5.1 C# engine, and its modding process differs from the original game.

Installing STS2 Mods Manually

For Slay the Spire 2, manual installation often involves downloading mod files, typically from platforms like Nexus Mods, and placing them into a designated folder.

1. Run the Game Once: Ensure you have run Slay the Spire 2 at least once to generate necessary game files. 2. Locate Game Directory: Find your Slay the Spire 2 installation folder. This is commonly found at Program Files\Steam\SteamApps\Common\Slay The Spire 2. 3. Create a 'mods' Folder: If one doesn't exist, create a new folder named mods within your Slay the Spire 2 game directory. 4. Download Mods: Acquire mod files, usually in compressed formats like .zip, from modding websites such as Nexus Mods. For manual installation, select 'Manual Download' on Nexus Mods. 5. Extract and Place Mod Files: Extract the contents of the downloaded compressed mod files. Then, place the extracted mod files (often .dll files along with mod_manifest.json and mod_image.png) into your SlayTheSpire2/mods folder.

Using STS2 Mod Manager

A dedicated mod manager for Slay the Spire 2, named STS2 Mod Manager, is available for Windows, macOS, and Linux. This manager simplifies the process of installing and managing modpacks.

1. Download and Run Installer: Download the appropriate installer for your operating system from the STS2 Mod Manager GitHub page and run it. 2. Auto-Detect Installation: The manager's first-launch wizard will attempt to auto-detect your Slay the Spire 2 installation via Steam. 3. Add Modpacks: You can add modpacks by pasting a share code or by browsing public modpacks directly within the application. The manager can automatically install bundled and GitHub-sourced mods. For Nexus-only mods, it will guide you to manually download the files, which its folder watcher will then pick up and install. 4. Launch Game: After selecting your desired modpack, hit 'Launch'. The manager will perform an auto-backup before launching the game.

Launching Slay the Spire 2 with Mods

After installing mods for STS2:

1. Start STS2: Launch the game as usual. You should receive a popup asking you to confirm that you want to use mods. The game may close and require reopening. 2. In-Game Mod Settings: Upon reopening, the game will load a separate save file for modded play, and a new 'Modding' or 'Mods' option will appear in the settings menu, where you can view your installed mods.

General Modding Tips and Troubleshooting

Backup Saves: Before installing any major mods or updates, it's a good practice to make a backup of your Slay the Spire save files.

Beta Branches (STS1): For the original Slay the Spire, ensure you are not on a beta branch of the game, as this can cause crashes when using mods.

Java for Manual Installation (STS1): If manually installing .jar files for STS1, ensure your system is set up to open .jar files with Java.

Mod Compatibility and Dependencies: Always check if mods have specific requirements or known compatibility issues. Many mods depend on ModTheSpire, BaseMod, or StSLib. Having conflicting mods or missing dependencies can prevent the game from loading or cause crashes.

Achievements: Modding Slay the Spire typically voids achievements. However, there may be specific mods available to re-enable them.

Enabling/Disabling Mods: The ModTheSpire launcher for STS1 allows you to toggle individual mods on or off before each run. For STS2, there's an in-game modding menu.

Recommended Mods for Slay the Spire (2025)

As of 2025, several mods are highly recommended by the community for the original Slay the Spire to enhance quality of life, add new content, or introduce unique challenges.

Minty Spire: A highly recommended Quality of Life (QoL) modpack that helps smooth out various aspects of the game.

Downfall: A significant content mod that allows players to play as the Spire's monsters.

Packmaster: A popular mod that adds new characters and content.

Spire with Friends: Enables a cooperative gameplay experience.

Permanent Neow: Another recommended mod.

Challenge The Spire: Introduces optional challenge modes with varying difficulty levels to the main menu, such as Elite Rush and Boss Rush.

The Servant: One of the earliest and best character mods, adding Sakuya from the Touhou games as a playable character.

Replay The Spire: Expands the base game with new content and can integrate with other mods.

Frequently Asked Questions

Q: Will modding Slay the Spire disable achievements? A: Yes, generally modding Slay the Spire voids achievements. However, there might be specific mods available to re-enable them. Q: Can I use mods on console versions of Slay the Spire? A: Unfortunately, modding Slay the Spire is primarily for PC players, and there are not many mods available for console versions. Q: What should I do if my game crashes after installing mods? A: First, ensure all required dependencies (like BaseMod and ModTheSpire for STS1) are installed and enabled. Check for any conflicting mods, especially if you have installed the same mod from multiple sources (e.g., Steam Workshop and manual download). If you're on STS1, make sure you're not on a beta branch of the game. Consider disabling recently added mods one by one to identify the culprit. Q: Do I need to re-enable mods every time I launch the game? A: For Slay the Spire (original), once you've selected and played with mods, your mod state is usually saved. If you haven't changed your mods, you can often just hit 'Play' in the ModTheSpire launcher. If it's your first time running ModTheSpire or you've added new mods, you'll need to enable them in the launcher. For STS2, there's an in-game modding menu to manage them.

Comprehensive Guide to Modding Slay the Spire (2025-2026)

Quick Summary