I agree that advertising FeralHeart with actual ads would be amazing, and yes it would help the game in many regards. I remember reading through Fonzie's thread a couple months back, but never commented. Guess I can say my peace now, eh?
I wouldn't leave the advertising solely to the staff. We as members of this community, staff or not, need to help spread the word that this little game exists. You can help by simply mentioning FeralHeart's name on another game or platform such as a forum or social media in the manner of "I play X game in my free time" or however else you would want to go about it, just as I do on my DeviantArt page.
To help advertise this game, you can make YouTube videos about FeralHeart. Maybe make a music video, or one that goes over all the fun and silly things that happen. Or, you could make one about all the cool and neat things you can do with this game, such as make and implement your own meshes, animations, textures, items, maps, presets, markings, everything. You can mention the game in your signature or bio on other platforms, too. (Doing this just as long as it's okay when on another game's forum. Always respect other's rules.) Generally, throwing out the name of something will gather interest if nobody has heard of it before. Be it in a discord server you're active in, a twitter post, tumbler post, on a forum--anywhere would do. If more of us started doing this wherever we can or want to, I'm sure FeralHeart's name will get around.
Needless to say, go for it! Tell other people about FeralHeart if you want to do that in hopes of helping it grow again. It's always fun to talk about games you love to others. Hopefully they'll want to experience the game as well with you. That's how games get around anyways~