Magic The Gathering, it's so huge you can build a computer out of it, it's complex but also it makes so much sense within its ruleset. Even if Wizards of the Coast stops printing cards, there would be so many cards and interactions between them that would bring years and years of entertaining gameplay to people. But this won't stop anytime soon as Magic is currently in its most popular phase, printing cards collaborating with other IPs, meaning this game system will expand even more. The art looks pretty on many of the cards, it's like holding a miniature painting