Does anyone know how to make the screen shot of your game appear in Google Featured Snippets ?

For the first version of my game it appeared, but then when I changed the screen shot it disappeared from the snippet

I investigated a bit more. I think the problem is that the screenshots have no title, alt tag and meaningless file names - that makes it very hard for google to figure out how to associate an image with the game. Also, the main image does not appear on the game page.

Finally, Google is showing a image in the featured snippet of my game. I am convinced now that the lack of the alt tag in the screenshots  is the problem.  The top banner has an alt tag with the name of the game, so that's the only thing that Google can pick up. Of course it has to crop the image, because the banner is too wide.

Yes alt tag is more important in eyes of google; in order to get featured snippet.. but you can use also schema to get featured snippet Check This Out example how i did..