One Step From Eden: How to Install Mods

To be able to use Steam Workshop mods, you must first subscribe to the mod you like on the respective Steam Workshop page. Steam will automatically download it for you the next time you open the game.

Then, simply open the game, select the mod that you want to activate, and press Install Mods.
Wait until it goes from (Installing) to (Install Complete~) and you’re good to go!

If you haven’t installed any mods before, including from the Steam Workshop, you might be getting a DirectoryNotFound Exception, as shown below, and/or a never-ending (Installing) button.

Exit the game and open the directory where you installed the game.
An easy way to get there is to do the following:

1. Right-click on the game in your Library list.
2. Click on Properties.
3. Click on Local Files.
4. Click on Browse Local Files….

You should now be at a folder that looks like this:
Then go into the OSFE_Data/StreamingAssets folder, and create a Mods folder in there.

Relaunch the game and enjoy your downloaded mods!

Note that even though the Mods folder needs to exist to use any mods, Steam Workshop mods are not downloaded to this folder. Instead, they’re downloaded to the workshop folder, steamapps\workshop\content\960690. The Mods folder is only used for installing local mods.

That’s just how the mod menu currently works. Rest assured that when you press Install Mods, all local mods within the Mods folder will be installed, along with any selected Workshop mods.
The only downside is that you can’t turn off a local mod within the menu.
You have to take it out of the folder or restart the game to disable it.