First of all, could you provide emulator with download of your game? I've played it on Visual Boy Advance, it is free (there are even open source emus). It would give easier time for players wanting to test your game.

Now to the meat - your game is pretty bare-bones. I mean it is playable, but I didn't have much fun. It is really remarkable, that you made it on GameBoy, so congrats for that ;)

The game is pretty unfinished, as you said. I would have liked to at least see the devil’s card after I played, because losing an L challenge with an ace or an H with a king happened so often that I thought I mistyped. Also, the "you win" and "you lose" messages appear too soon, so I couldn’t even enjoy the end-of-game artwork!

I played your game on BizHawk, it ran smoothly.

wow making a game boy game kodos man... Hope you learned alot!!! Thats what game jams are for. Maybe adding a goal to reach (like score 100) would have made the game. Apart from that the game is suprisingly fun. This concept can be build upon to make a hyper casual game.

Good Job!!! Keep it up

Your game seems to have a nice catch to it, I'm no good with emulators, how they work and by so I haven't played it, but from the itch.io page, the cards mechanics seem really nice. I wanted to ask you how you managed to put in the jam a game you had to work through 6 days. did you add more things after the jam ended or did you start earlier? Or that was a typo? if so, fix it in the description or people might think you didn't meet the parameters of the jam at all. I'll be back with a gameplay review as soon as i get an emulator running