it's so funny to me that the tetris company made up june 6 1984 as its birthday because of E3 2009 and now they're committed to the bit. they even made a whole movie!
but, it's probably illegal to lie on the copyright date - it's always 1985 there, which matches up with literally every news article I'm aware of written before 2009, an interview with alexey, vadim's website prior to 2009, and more.