Initially intended for completion in June 1994, and later in September of that year, development of the game took 21 months, with time constraints and a limited development team leading to numerous production difficulties. The game's lead character was intended as a mascot for the developer who could rival the likes of other immensely popular platformer characters – primarily Mario and Sonic the Hedgehog. Gex was created by Lyle Hall in 1993 shortly after he had joined Crystal Dynamics, and initially followed a movie stuntman named Gecko X before being retooled at the advisory of lead programmer Gregg Tavares.

It is the first in the Gex series of video games, and introduces players to the title character, a wisecracking, television-obsessed gecko voiced by comedian Dana Gould, who must venture through the 'Media Dimension' and defeat Rez, the overlord of the dimension who wants to make Gex into his new network mascot.

It was a pack-in game for Panasonic models of the 3DO later in the console's life. It was originally released for the 3DO in 1995 ports of the game for the PlayStation and Sega Saturn were later developed by Beam Software, and a PC version was licensed by Microsoft and released for Microsoft Windows. Gex is a platform game developed by Crystal Dynamics.

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