WarGames
Keep your MCUs and your DCEUs. The only cinematic universe I’m interested in is the Snarky Teenage Broderickiverse, or STBU. Predating Ferris Bueller by 3 years, WarGames gets the universe off to a good start with an irresistible, unfortunately timely premise: What if a young hacker thought genuine government weapons were a computer game, and accidentally started World War III?