In 1990, Sega of Japan president Hayao Nakayama decided Sega needed a flagship series and mascot to compete with Nintendo's Mario series. Nintendo had recently released Super Mario Bros. 3, at the time the bestselling video game ever. Sega's strategy had been based on its earlier release of the Sega Genesis in the 16-bit era and its reliance on its successful arcade business to port games to the console. However, Nakayama recognized that Sega needed a star character in a game that could demonstrate the power of the hardware of the Sega Genesis. Sega's mascot, Alex Kidd, was considered too similar to Mario. Several character designs were submitted as part of a contest; the winning character was a teal hedgehog created by artist Naoto Ohshima. The gameplay of Sonic the Hedgehog originated with a tech demo created by Yuji Naka, who had developed an algorithm that allowed a sprite to move smoothly on a curve by determining its position with a dot matrix. Naka's original prototype was a platform game that involved a fast-moving character rolling in a ball through a long winding tube, a concept fleshed out with Ohshima's character design and levels conceived by designer Hirokazu Yasuhara.