Convert GSLIDES to PPT

Converting Google Slides Shortcuts directly to Microsoft PowerPoint Presentations (.gslides to .ppt conversion) is, per se, not possible, since the .gslides shortcuts do not contain any multimedia data. They merely link to an existing Google Slides object located on your Google Drive. 

Simply open your presentation using the .gslides shortcut, then download it in a .ppt format via the 'File -> Download As' function.