After its invention, Tetris spread as shareware throughout the socialist world, and for a time it was impossible for any firm in the capitalist world to own exclusive rights to its distribution. The story of Tetris is a story capitalist appropriation and enclosure of the commons
With glasnost and the dismantling of the soviet union, several people tried to make money by taking advantage of the situation and of the lack of established intellectual property frameworks, claiming to foreign buyers that they held the right to sell the Tetris "IP" to them.
Multiple of these buyers therefore independently claimed they owned Tetris, and sold their separate versions of the game. It took many legal battles for one corporation, Nintendo, to eventually come out on top.
Today they've made their own version of history the "official" one