The art is great, as others have mentioned. I guess the card gameplay itself has been uploaded after the jam deadline like you mentioned, so I'm not sure if it counts but, I kinda didn't really understand it very much anyway. I got stomped in my first few matches because my hand would eventually fill up with 0 atk / 0 def (or 1 atk / 1 def) cards and it felt like the enemy almost never had those, haha. Maybe it's a skill issue
The visuals and audio make for a great atmosphere, this is a really cool skeleton for a game that has a lot of potential. I'm not sure how it follows with the theme (and I'm not sure if it's an incremental game?) but for what it is, it was a pretty neat little experience (at least in its current state)