Slay the Spire 2 Mods — How to Install DLL and PCK Mods Safely

The Steam Workshop for Slay the Spire 2 hosts the loader mods, but community mods still circulate as DLL + PCK file pairs. Installing them is a two-minute job — the part people skip is the save backup, and that's exactly the part you can't skip: the first mod install resets local profile saves.

Step 1: back up your saves (mandatory)

Copy this folder to another drive or a USB stick:

C:\Users\<YourName>\AppData\Roaming\SlayTheSpire2\steam\<YourSteamID>

Inside are profile1 / profile2 / profile3 — your three save slots (see save file location for details). The first mod install is the dangerous one; after a modded launch has succeeded once, adding or removing mods no longer wipes saves.

Step 2: get the mod files

Download mods from a source you trust — usually a .zip archive. Unpack it: the two files that matter are the DLL and the PCK. Nothing else needs to move.

Step 3: install into the mods folder

1. Open the game's local folder: Steam → right-click the game → Manage → Browse local files.
2. In the game root, create a folder named mods (lowercase).
3. Drag the DLL and PCK files directly into mods — no nested subfolders.
4. Launch the game through Steam. Mods load automatically.

Step 4: unlock everything (optional)

On the main menu, press ~ (the tilde key, left of 1), type:

unlockall

and press Enter. All characters, cards, relics and modes unlock on the spot — handy for testing mods on a fresh profile.

Troubleshooting rules

• Wrong folder is the #1 failure: mods must be in the game root, files flat inside it.
• One to two mods at a time: conflicts are common; when the game breaks, remove mods until it doesn't.
• Version matching: mods built for old game versions crash on launch — re-download mods after big patches.
• Multiplayer: modded builds break co-op sync; keep mods out of party lobbies.

Keep reading:

• Console Commands
• Save File Location
• Launch and Crash Fixes