This is something i've been frustrated with for years, there isn't a proper tagging system for screenshots/excerpts/promos/adverts for furry games. I guess that in the past, the flash tag was a pretty decent way at getting towards playable content but since its death, and I guess the conception of exe files there is no way to find games on this site except through direct knowledge. Pretty much, anything that is/or links/alludes to a playable furry game should be tagged properly so that this sort of content is archived.
Below are examples, with query tags shown of posts that are of playable games/content. As you can see there are no tags indicating that these are playable games, you have to find them through a combination of tags.
https://e621.net/posts/3543664?q=dudemantix
https://e621.net/posts/3755624?q=vr+animated
https://e621.net/posts/2474267?q=animated+pixel_%28artwork%29+rape