Originally, the game was about a stunt man named Gecko X, who worked for a studio that was in financial trouble due to the main antagonist, Karl Chameleon. Each level would be themed around a Hollywood action movie genre, which would show stock footage of old Hollywood movies at the beginning and allow Gex to run around and do "stunts". The better the player did in the level, the more money the "Movie" made and therefore the better the studio did.

The idea was dropped because the developers found it hard to base a game around a real world theme while still making it believable and fun, compared to Mario and Sonic, which were based in fantasy settings and therefore nothing that appears in the game needed to be explained. The change in plot and setting to 'TV Land' allowed the developers to have this fantasy setting and some freedom to do whatever they wanted.

Lead Designer Justin Knorr, frustrated with all the cuts being made to get the game to ship, put a series of hidden messages for players to find. The first messages told the player how to access a secret level select screen, and encouraged them to pick a specific level, in which he placed more messages berating the company for cutting so much content. He included the head of product development's phone number, and suggested players call it and complain. The playtesters found these messages, and Justin was fired.

There is a secret portal located towards the upper-left corner of the level "The Project". Going in it will take Gex to a hidden room with a unique enemy blocking an exit to the level; a random man walking towards Gex. Hitting the man will cause him to vomit, and his kill animation shows large amounts of blood shooting out of his neck before dying. It's unknown who this person is, though it could be a self-insert by one of the game's developers.

The map for the level "The Project" features the hidden message "PHAT CITY".

Exclusive to the 3DO version, in the level "The Project", there is a secret exit in the bottom-left corner of the map with a Question Mark caption just before it reading:


Entering this secret exit will boot up a 3D side-scrolling shoot-'em-up level. The game gives you 5 credits and 3 hit points to play through the game. You can pick up remote controls, and after getting enough of them your ship will now have triple shots. For every enemy shot at, the score will change to different quips and numbers at random, including:

•"69 Dude!"
•666 (the Number of the beast)
•90210 (the zip code to Beverly Hills, California and a reference to the 1990 television series "Beverly Hills, 90210")
•"Googleplex" [sic] (Googolplex, the company Google did not exist at the time this demo was made or when Gex was first released)
•"Really high!"
•"Way up there"
•"Astronomical"
•Infinity
•"Score is cool, huh, huh"
•"Are you still counting?"
•"I don't know"
•"I lost count"
•"Who cares!"
•"Who keeps score!"
•"Missed one!"
•"Watch your butt not the score!"
•"Is your controller plugged in"
•"Loser!"
•"You suck!"
•"Sucks to be you!"
•"How bad are you?!"

It was originally a senior college project for Stanford University by programmer Evan Wells, but was repurposed as an Easter egg for this game. On the Game Over screen, the game's credits can be seen:


This Easter egg was first known to have been documented in a pair of grainy YouTube videos from 2007. It's unknown why this minigame was not included in other versions of the game.

Exclusive to the 3DO version, in the level "The Project", there is a secret exit towards the bottom of the map with a Question Mark caption just before it reading:


Going through the secret exit will boot up a secret Breakout clone, where you control Gex shooting balls up towards isometric cubes. To catch the ball, it must hit Gex's head, or if it is too far away from his head, Gex can shoot his tongue out a short distance to catch it just before it lands. The game's second boss, The Flatulator, also appears in this minigame, and hitting him with the ball will allow Gex to shoot the ball higher, while propellors will occasionally appear to generate more cubes.

This game appears to be another small project that was repurposed into an Easter egg, although there are no known messages or credits that appear during it. It's unknown why this minigame was left out of other versions of the game.

The game's instruction manual features an extensive backstory for Gex, who lived in Maui with his mother and siblings, whilst his father was working at NASA. Due to an incident involving a band-aid floating in a fuel tank, Gex's father was killed, causing Gex to become a shut-in, sitting and watching TV all day.

After moving to California and his mother selling the TV away, Gex runs away from home and sleeps in the garage of a local punk he befriends. At his deteriorated state, Gex imagines an invisible friend known as "The Mayor." With another death in the family, this time being Gex's Uncle Charlie who was the original model for the Izod shirt logo, this leaves Gex's family with an inherited fortune of 20 billion dollars.

With his share of the money, Gex leaves his family behind, returns to Maui, and purchases a mansion with the largest TV set in the world and enough food to last him for decades, so that he'll never have to leave the television again.