Realizing that completed lines filled the screen quickly, Pajitnov decided to delete them, creating a key part of Tetris gameplay. This early version of Tetris had no scoring system and no levels, but its addictive quality distinguished it from the other puzzle games Pajitnov had created. Pajitnov had completed the first playable version of Tetris by June 6, 1984. Pajitnov presented Tetris to his colleagues, who quickly became addicted to it. It permeated the offices within the Academy of Sciences, and within a few weeks it reached every Moscow institute with a computer. A friend of Pajitnov, Vladimir Pokhilko, who requested the game for the Moscow Medical Institute, saw people stop working to play Tetris. Pokhilko eventually banned the game from the Medical Institute to restore productivity. Pajitnov sought to adapt Tetris to the IBM Personal Computer, which had a higher quality display than the Electronika 60. Pajitnov recruited Vadim Gerasimov, a 16-year-old high school student who was known for his computer skills. Pajitnov had met Gerasimov before through a mutual acquaintance, and they had worked together on previous games. Gerasimov adapted Tetris to the IBM PC over the course of a few weeks, incorporating color and a scoreboard. Acquisition of rights by Mirrorsoft and Spectrum HoloByte Pajitnov wanted to export Tetris, but he had no knowledge of the business world. His superiors in the Academy were not necessarily happy with the success of the game, since they had not intended such a creation from the research team. Furthermore, copyright law of the Soviet Union created a state monopoly on import and export of copyrighted works, and the Soviet researchers were not allowed to sell their creations. Pajitnov asked his supervisor Victor Brjabrin, who had knowledge of the world outside the Soviet Union, to help him publish Tetris. Pajitnov offered to transfer the rights of the game to the Academy, and was delighted to receive a non-compulsory remuneration from Brjabrin through this deal. In 1986, Brjabrin sent a copy of Tetris to Hungarian game publisher Novotrade. From there, copies of the game began circulating via floppy disks throughout Hungary and as far as Poland. Robert Stein, an international software salesman for the London-based firm Andromeda Software, saw the game's commercial potential during a visit to Hungary in June 1986. After an indifferent response from the Academy, Stein contacted Pajitnov and Brjabrin by fax to obtain the license rights. The researchers