A Video Game trope where the game's setting (e.g. combat system) doesn't involve actual cards, but the mechanics the game uses to implement its system use cards anyway. In other words, these cards exist outside the universe's Fourth Wall, and are invisible to the in-universe characters; who are still clashing swords and summoning spells, not slapping cards down on some table. Expect to see one character with full Medium Awareness of the subject, solely to teach the player how the battle system works. After that, the card system is (almost) never explicitly mentioned again.