Back in 1993, the Senate hauled video game executives into hearings over Mortal Kombat and threatened a federal ratings law. Within a year the industry created the ESRB, its own ratings board. Congress shelved the bill. Thirty years later there's still no federal video game law. Hollywood ran the same play in 1930 with the Hays Code. Comic books did it in 1954 with the Comics Code. The pattern is nearly a century old. When Washington starts drafting rules for your industry, you hand them a…