Steam Play is initially available only for titles that have been whitelisted by Valve. To install Nimble Writer on using the Linux Steam client, the first thing you'll need to do is Enable Steam Play for all titles.

Steam > Settings > Steam Play

Ensure "Enable Steam Play for all titles" is checked.

After restarting the Steam client, you will be able to install Nimble Writer from your Library.

Note: This method is helpful for determining the appid for Steam titles and to follow the process of modifying Proton wine prefixes, but Method 2 below is easier and only requires the Winetricks package.

As of this guide's writing, the Microsoft .NET Framework will need to be installed to the WINE prefix for Nimble Writer after initial setup via Steam Play. Otherwise, Nimble Writer may exit before the program can fully start up while running in Linux.

There are several ways to do this, but one of them is detailed below.

First, you will need to find a way to select the correct WINE prefix and modify it using Winetricks. This method will require the following software packages as prerequisites:

• Winetricks https://github.com/Winetricks/winetricks
  
• Python (version 3 or later) https://www.python.org
  
• Protontricks[github.com] (Update 8 Feb 2019: Original Protontricks repository is no longer maintained. Users might want to check out this fork[github.com] as an alternative.)

See the web sites listed above for information about installing the listed packages.

Once the above software is installed, we'll need to determine which WINE prefix to modify using Protontricks. Open a Terminal window and use the command:

$ protontricks -s Nimble


This tells us that the APPID for Nimble Writer is "348200" (note that we can also get this ID from Nimble Writer's URL on the Steam Store). It also confirms that Protontricks can see our Nimble Writer installation.

Now we need to install/repair the Microsoft .NET Framework installation for the APPID we just found. Using the result from the previous command, we enter:

$ protontricks 348200 dotnet40


While this runs, we may be prompted to Install/Repair the .NET Framework. Follow the prompts to complete the process.

After the process is complete (it may take several minutes), assuming there are no insurmountable errors, we are greeted once again with the command prompt.


Close the Terminal window, and now we can run Nimble Writer from the Linux Steam client.

Using some of the information that is discovered using Method 1 above, we can accomplish the above using only Winetricks from the command line.

You'll need to know:

• Your Steam Path, which will contain the "steamapps" folder (e.g. "/home/.steam/steam/").
  
• Your Proton Version (find this in the "[steampath]/steamapps/common" folder)
  
• Note: We already know from Method 1 above that Nimble Writer's appid is 348200.

$ env WINEPREFIX="[steampath]/steamapps/compatdata/348200/pfx" WINEPATH="[steampath]/steamapps/common/[ProtonVersion]/dist/bin/wine" winetricks dotnet40

Follow the prompts to complete the process and install the .NET Framework. Close the Terminal window, and now we can run Nimble Writer from the Linux Steam client.