Issues loading save games in the GOG.com version (Even after Patch 1.6.2f3)

Issue Description

Versions 1.6.2f1 & f2 when released on GOG.com had a bug which would prevent loading of save games from the load game menu. This was fixed in Patch 1.6.2f3, however in some cases upgrading will not fully resolve the issue.

Cause

It is believed this is caused by leftover files from previous versions which prevent the fix from fully applying. 

Current Status

This issue is resolved in Patch 1.6.2f3 however it is advised rather than simply updating an existing version to the new version of the game you perform the following steps to ensure a clean install occurs.

Clean Install Steps

Thank you to various GOG Community members for providing these steps and also to Pejorative to summarizing them as follows:

 Step 1: Uninstall the game but make a backup of your saves folder in your WftO/gamedata/maps directory 

Step 2: Use the latest version of CCleaner to clean your files and registry. 

Step 3: Install the latest version of the game from GoG 

Step 4: Copy your saves back to the maps directory