they DID add those crossover decks recently, and the dev has indicated that there is more additional content coming. Idk, I think having the cards in HD wouldn't look right, because the entire game has a specific kind of pixel art. Even the smooth, swirly background has a pixel art filter on it, bc that's the vibe that the dev really wants the game to have. Mixing them would be like when pixel art rpgs have super hi-res fonts. It just doesn't fit right.