Back in 1993, the Sega Technical Institute worked on a game being developed for the Sega console of the time, the Genesis (or Mega Drive as known in some countries of the world). The game was initially titled "Segapede", though it was later reworked into the name of "Astropede".

The game was set to take place in the same universe as the Sonic franchise, featuring a badnik created by Dr. Robotnik named "Zipp", in an adventure to collect and cleanup something called "Chaos Dust" that infected an evil doctor (most likely Robotnik/Eggman himself). The gameplay was going to be similar to Sonic's, featuring momentum-based mechanics, but with the twist that Zipp would be able to gain abilities (like power-ups), that would change its back segment depending on the power up, like Defensive Spikes, Turbo Charger, Pulse Cannon, and many others.

Craig Stitt, an artist involved in the development of Sonic 2, pitched the idea for the game to Sega, with an initial proposal made in September of 1993, and after making a first playable version of the game (and dropping the Sonic connection), it was greenlit for production in November of 1993, this time under the name of Astropede. However, the game would be cancelled in 1994, due to the sheer amount of games that the Sega Technical Institute (STI) was working at during that time span.

The prototype features some familiar artwork, reusing assets from the dropped Sonic 2 level, Hidden Palace Zone (which Craig Stitt worked on), for the playable demo that was pitched. And thanks to Craig Stitt himself, the game's prototype was shared, dumped and preserved!
Here's some notes that Hidden Palace gives about the prototype ROM:

• Original concept was pitched on September 21, 1993 to Sega sometime after work on Sonic Spinball had finished. The project was revised and approved for "first playable" status in November 22, 1993.
• Game was eventually cancelled sometime after mid 1994 due to the need of having staff on other projects.
• Game ROM is from 1994, possibly just before the game was cancelled.
• Game consists of 1 level with music and sound done by Howard Drossin.
• Game's first level uses level art from Hidden Palace Zone, a cut level from Sonic the Hedgehog 2 for the Sega Mega Drive.
• Pressing start resets the game.

The prototype is currently preserved and available over at the Hidden Palace website for everyone to experience.

Source
Release Page

 

[urbanman2004]

Another win for game history preservation

 

[Luke94]

Was it leaked by one of former Sega Technical Institute employees? Who was it Michael Kosaka,Offer Alon,Chris Senn,Christina Coffin or someone else?

 

[GameGeek]

For a start you are totally wrong about Brazil
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And Argentina

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I'm from Argentina and it was definitely called Genesis here, at least in the late 90s.

 

[sarkwalvein]

I'm from Argentina and it was definitely called Genesis here, at least in the late 90s.

I am from Argentina, it was called Megadrive when it arrived, and when I bought it in 1992. "Genesis" named models only arrived after the console prime when the PS1 was already broadly adopted.