Docs, StS: Document setup for Slay the Spire GOG/Game Pass installations (#1913)

Co-authored-by: KonoTyran <Kono.Tyran@gmail.com>

worlds/spire/docs/slay-the-spire_en.md

@@ -2,12 +2,36 @@
 
 ## Required Software
 
-For steam-based installation, subscribe to the following mods:
+For Steam-based installation, subscribe to the following mods:
 
-- ModTheSpire from the [Slay the Spire Workshop](https://steamcommunity.com/sharedfiles/filedetails/?id=1605060445)
-- BaseMod from the [Slay the Spire Workshop](https://steamcommunity.com/workshop/filedetails/?id=1605833019)
-- Archipelago Multiworld Randomizer Mod from
-  the [Slay the Spire Workshop](https://steamcommunity.com/sharedfiles/filedetails/?id=2596397288)
+- [ModTheSpire](https://steamcommunity.com/sharedfiles/filedetails/?id=1605060445)
+- [BaseMod](https://steamcommunity.com/workshop/filedetails/?id=1605833019)
+- [Archipelago Multiworld Randomizer](https://steamcommunity.com/sharedfiles/filedetails/?id=2596397288)
+- (optional) [Downfall](https://steamcommunity.com/sharedfiles/filedetails/?id=1610056683)
+- (required for downfall) [StSLib](https://steamcommunity.com/workshop/filedetails/?id=1609158507)
+
+For GOG or Xbox PC Game Pass installation:
+
+1. Download the official Steam Console Client [SteamCMD](https://steamcdn-a.akamaihd.net/client/installer/steamcmd.zip).
+2. Unpack that .zip file into some folder and double-click on `steamcmd.exe`.
+3. The client will now update itself. When it's ready type `login anonymous`. Now you are ready to download the actual
+    mods.
+4. Run the following commands to download the required mod files:
+  - Mod the Spire: `workshop_download_item 646570 1605060445`
+  - BaseMod: `workshop_download_item 646570 1605833019`
+  - ArchipelagoMW: `workshop_download_item 646570 2596397288`
+  - (optional) Downfall: `workshop_download_item 646570 1610056683`
+  - (required for Downfall) StSLib: `workshop_download_item 646570 1609158507`
+5. Open your Slay the Spire installation directory. By default on GOG this is `C:\GOG Games\Slay the Spire`, on PC Game
+    Pass this is `C:\XboxGames\Slay The Spire\Content`.
+6. In the folder where you unzipped SteamCMD there will now be a `steamapps` folder. Copy ModTheSpire.jar from
+    `steamapps\workshop\content\646570\1605060445\ModTheSpire.jar` to your Slay The Spire installation directory.
+7. Create a folder named `mods` inside the Slay the Spire installation directory. Each folder inside
+    `steamapps\workshop\content\646570` will have a single .jar file. Copy each of them except ModTheSpire.jar into the
+    `mods` folder you made.
+8. Now open Notepad. Paste in the following text: `jre\bin\java.exe -jar ModTheSpire.jar`. Go to "File -> Save as" and
+    save it into your Slay the Spire installation directory with the name `"start.bat"`. Make sure to include the quotes
+    in the file name!
 
 ## Configuring your YAML file
 
@@ -25,12 +49,21 @@ the [Slay the Spire Settings Page](/games/Slay%20the%20Spire/player-settings).
 ### Connect to the MultiServer
 
 For Steam-based installations, if you are subscribed to ModTheSpire, when you launch the game, you should have the
-option to launch the game with mods. On the mod loader screen, ensure you only have the following mods enabled and then
-start the game:
+option to launch the game with mods.
+
+For GOG or Xbox PC Game Pass intallations, launch the game by double-clicking the `start.bat` file you created earlier
+which will give you the option to launch the game with mods.
+
+On the mod loader screen, ensure you only have the following mods enabled and then start the game:
 
 - BaseMod
 - Archipelago Multiworld Randomizer
 
+If playing with Downfall, also make sure the following are enabled:
+
+- Downfall
+- StSLib
+
 Once you are in-game, you will be able to click the **Archipelago** menu option and enter the ip and port (separated by
 a colon) in the hostname field and enter your player slot name in the Slot Name field. Then click connect, and now you
 are ready to climb the spire!