demonstrating the multiplayer features. The prototype featured the Feather item from Super Mario Kart and a Magikoopa as one of the eight playable characters, who was replaced with Donkey Kong in the final game. The player's driving controls were designed to be similar to operating a radio-controlled car. Mario Kart 64 features tracks that are fully rendered in 3D, and billboarding to display the characters and items through the use of Advanced Character Modeling (ACM), the MIPS CPU, and Silicon Graphics workstations. Konno stated that, though rendering the characters as 3D models was not impossible, the display of eight simultaneous 3D characters would have exceeded the processing power of the console. Instead, the characters are composed of pre-rendered sprites that show the characters from various angles to simulate a 3D appearance, similar to Super Mario Kart, Killer Instinct, and Cruis'n USA. Rare, developer of the Donkey Kong Country games, provided Donkey Kong's character model. Halfway into the game's production, the developers suffered a hard disk crash, causing the original character models to become lost. They were forced to remake "about 80%" of the character models, and updated the character select screen to have them animated instead of still, which was not in the original plans. The technique of rubber band AI prevents all the racers from easily separating, and the Spiny Shell item, which targets and attacks the player in first place, was added in order to keep each race competitive and balanced. The item was included in all subsequent Mario Kart games. Soundtrack The soundtrack for Mario Kart 64 was composed by Kenta Nagata, which is his first work on a Nintendo game. The soundtrack was released several times in different formats including compact disc and audio cassette. Four different versions of the album were released: Race Tracks and Greatest Hits Soundtrack in North America; Original Soundtrack and Club Circuit were released in Japan. It was later released in a three disc collection, along with the soundtracks of Star Fox 64 and Super Mario 64. Release In addition to the regular release in Japan, Nintendo released a "limited edition" which was the regular cartridge bundled with a black-and-grey Nintendo 64 controller. The Japanese release in December 1996 was followed by a U.S. release in February 1997. Nintendo of America chairman Howard Lincoln stated that in addition to the time needed for the localization, Mario Kart 64 was more critical