Finding the manifest ID (skip if wanting pre-dlc patch)

First thing to do when downpatching is to know what patch we want to download. To do that we are going to head to SteamDB which shows all the manifest ids of each version. Using the date to know which one you want to download is important, and the manifest id for the pre-dlc patch is 6373578051578530455.

Opening the Steam Console

Now to download the version of the game we want, we need to open the steam console. The most convenient way of doing this is by typing "steam://nav/console" into a browser, and allowing it to open steam. You can also get to the console by pressing WinKey+R to open the run prompt, and then type the same thing, "steam://nav/console".

Downloading the downpatched version

To download a specific version of the game, the command is as follows.

download_depot 2513280 2513281 <manifest-id>

For the pre-dlc patch, we replace the manifest id.

download_depot 2513280 2513281 6373578051578530455

Now, all there is to do is wait until steam finishes the download before the next step. Dont worry, the console will let you know when its done!

Setting up the game

After the download is complete, you'll want to head to "C:\Program Files (x86)\Steam\steamapps\content\app_2513280\depot_2513281" to find the folder the downpatch is located in. If you dont see the game executables, then the download is not complete and you need to wait longer. Assuming you do see them, you'll want to right click, and create a new text document. Name the document "steam_appid", and place the following string of numbers inside the text file, "2513280" (no quotes), and save the file. Now, steam wont open the current version of the game if you launch the executable through this folder. Your folder after this step should look like this image.

Setting up a shortcut through steam

Since we have to launch the game through a shortcut, the most convenient way for me is to make it open through steam, but you can also create a shortcut on your desktop or taskbar. To create a shortcut through steam, you want to go to your library, and in the bottom left is a button that says "Add a game". Click this, and then select "Add a non-steam game", and browse to find the "SONIC_X_SHADOW_GENERATIONS.exe" app in the downpatch folder. After adding that program to steam, there will be a game in your library named SONIC_X_SHADOW_GENERATIONS which will open the downpatched version, with no conflicts to any current version you may have installed. You can rename this game by right clicking, and going to properties if you want!