Tetris is created in Moscow
Alexey Pajitnov completed the first playable version of Tetris on June 6, 1984 on an Elektronika 60 computer in the USSR — the falling-block puzzler that became one of the best-selling games of all time.
Source: Wikipedia — Tetris: 'It was released on June 6, 1984'; Guinness World Records — 'first released on 6 June 1984'