Gex: Enter the Gecko

The player controls Gex, an anthropomorphic gecko who runs, jumps, and attacks his way through television-themed levels. Gex can perform a tail whip attack, a tail bounce, and a flying karate kick, and he can climb certain walls and ceilings, a quality shared with real-life geckos. Gex's attacks can inflict damage on enemies, activate icons in the hub world that provide helpful hints, and break small TV sets that contain different colored flies, which, when consumed, can add an extra health point, add an extra life, unlock temporary upgrades, add oxygen in the outer space levels, or mark a level checkpoint. Specific stages require the player to collect power-ups to move throughout the level or to stay alive, as is the case with the futuristic stages in which the player must collect cyber energy to activate certain jump pads and bridges. While the majority of enemies can be defeated using Gex's move set, others must be eliminated by manipulating objects or machinery.

TV sets act as level entrances in the hub world, which expands as the player collects remotes and defeats boss enemies. Completing level objectives grants red and silver remotes in normal stages and gold remotes in bonus stages. Red remotes are collected by standing on a green button in front of in-world television sets after meeting level-specific objectives, which can be completed in any order, after which the player is transported to the hub world. Each normal stage has two silver remotes: one is hidden in the level, and another is awarded when the player collects 120 collectibles.

Following his victory over Rez in the Media Dimension, Gex (voiced by comedian Dana Gould in the North American release, Leslie Phillips in the European release, and Mitsuo Senda in the Japanese release) has retired from the public eye and turned to solitude.

Two years later, Gex has his quiet life turned upside down when one day he is watching television when all of a sudden, it goes blank and Rez's image begins flashing on the screen. Two government agents appear and explain that Rez has returned and they need Gex's help in taking him down again. Gex refuses, saying that he has already saved the world once and that they should try to find someone else. In response, the agents abduct Gex to their headquarters, in which Gex is interrogated.

In early 1997, Crystal Dynamics announced that they were working on a 3D sequel to Gex in the style of Super Mario 64. They originally intended to debut the sequel with the technology available at the time. Lead programmer Adrian Longland recalled: "It actually started as a 2D game and after three months we had a prototype with Gex jumping around and using this hover mechanic. Then E3 came along and suddenly it was, 'Okay, Crash Bandicoot shows you can do 3D graphics on the PlayStation and Mario 64 has this open world... let's put those two together for Gex!"

Rather than a grouping of polygons, Gex was built with a full skeletal system, with more bones than a real gecko, and a 'skin' stretched over-top to eliminate pop and tearing. This allows his mouth to move with the voiced dialogue.

The PlayStation version received favorable reviews, while the Nintendo 64 versions received mixed reviews, according to the review aggregation website GameRankings.

Critics almost unanimously described the levels as extremely well-designed, varied, and expansive. Dan Hsu of Electronic Gaming Monthly (EGM) said that ninety percent of what made Gex: Enter the Gecko fun was the level design with its wealth of imagination and diverse, humorous settings. IGN said the variety of objectives in each level was what set the game above most platformers. The graphics were also uniformly praised, with Jeff Gerstmann of GameSpot describing the overall look and frame rate as "about as close to Mario 64 as you'll ever get on a PlayStation" and Hsu's co-reviewer John Ricciardi commenting that "Gex's gorgeous graphics really exemplify just how far the PS has come since its release.