and the Neo Geo CD in 1994. Costs of these add-ons were generally high, nearing the same price as the console itself, and with the introduction of disc-based consoles in the fifth generation starting in 1993, these fell by the wayside. Nintendo had initially worked with Sony to develop a similar add-on for the SNES, the Super NES CD-ROM, but just before its introduction, business relationships between Nintendo and Sony broke down, and Sony would take its idea on to develop the fifth generation PlayStation. Additionally, Philips attempted to enter the market with a dedicated CD-ROM format, the CD-i, also released in 1990, that included other uses for the CD-ROM media beyond video games but the console never gained traction. The fourth generation had a long tail that overlapped with the fifth generation, with the SNES's discontinuation in 2003 marking the end of the generation. To keep their console competitive with the new fifth generation ones, Nintendo took to the use of coprocessors manufactured into the game cartridges to enhance the capabilities of the SNES. This included the Super FX chip, which was first used in the game Star Fox in 1993, generally considered one of the first games to use real-time polygon-based 3D rendering on consoles. Handhelds of the fourth generation Nintendo brought its experience from the Game & Watch series to develop the Game Boy system in 1989, with subsequent iterations through the years. The unit included a LCD screen that supported a 4-shade monochrome pixel display, the use of a cartridge-based system, and the means to link up two units to play head-to-head games. One of the early packages included Tetris bundled with the unit, which became the Game Boy's best-selling game and led the unit to dominate handheld sales at the time. The Game Boy also introduced the Kirby franchise worldwide, which became a staple of Nintendo's handheld consoles. The Atari Lynx was also introduced in 1989 and included a color-LED screen, but its small game library and low battery life failed to make it competitive with the Game Boy. Both Sega and NEC also attempted to compete with the Game Boy with the Game Gear and the TurboExpress, respectively, both released in 1990. Each were attempts to bring the respective home console games to handheld systems, but struggled against the staying power of the Game Boy. Fifth generation (1993–2006) During this time home computers gained