Slots and Skulls hasn't gone through Steam's official Steam Deck compatibility review yet, so the rating shows as "Unknown" and you won't see an automatic badge on the store page. I don't want that to be misleading, though.
As someone who loves playing games on Steam Deck myself, I've been testing on it regularly since the earliest stages of development. So far I haven't run into any compatibility issues, controls, text readability, and performance all work smoothly on Steam Deck.
I'll keep this page updated until we get the official "Verified" rating. If you do run into any issue on Deck, please let us know and we'll look into it right away. - Furkan