HOWTO for downloading and installing the Crossfire GTK2 client on Windows 10 (running Windows 10 Pro Insider Preview, Evaluation copy, Build 10130)
Visit the Crossfire website (http://crossfire.real-time.com/) for a link to download the GTKv2 Client for Windows (http://www.meflin.net/crossfire/crossfire-client-windows-1.60.2.exe)
When the download has finished, click on the Run button to start the installation process
If you see an alert about installing the client because it is from a unknown publisher, click the Yes button
The first screen of the installation process will state "Welcome to the Crossfire GTK2 Client Setup Wizard" - click the Next button to continue
Read through the License agreement, and if you accept, click on I Agree button
Select an installation directory - the default location should be fine, click on the Install button
Wait for the client to install - this should only take a moment
After the installation has completed, you will be prompted about running the client and viewing the Readme, click the Finish button
The GTK2 Client is now up and running
On the Metaserver Selection screen, left click once on a server and then click on the Connect button to connect & play on that server
Sample screen shot of the client running on Windows 10, using gtk-v1.glade layout and fog of war enabled