Big Guns (Exodus) is a cancelled shooter / action game that was in development by Neversoft Entertainment in 1996 / 1997. They were able to create a good-looking playable tech demo for this project that was shown to Shiny Entertainment on June 1996 to demonstrate their 3D engine in hopes that Shiny would hire them to develop the MDK Playstation port.
As we can read at the Playstation Museum, a coop mode was also available:
Exodus features a fast and furious two player cooperative play. Two player mode does not suffer from any slowdown as a result of the superior 3D engine. What makes Exodus stand out is that both players can combine their mechs into one larger mech. In transformation mode, player one would control the bottom half of the mech including walking and firing at enemies while player two would control the upper half which allows for 360 degree swivel as well as firing upon enemies.
Shiny was impressed with their technology and Neversoft started to work on the MDK conversion (that used the Big Guns engine), while the Big Guns concept was sold to Sony Computer Entertainment America.
Big Gus was meant to be published by SCEA in 1998, but 1997 was a tumultuous year for Neversoft. The MDK conversion took far longer than expected, and Big Guns, renamed Exodus, went through numerous design changes at the behest of Sony. Somehow Exodus was changed from a mech shooter to an action adventure featuring a cat-girl (sadly, we don’t have any image from this version of the game). The project was doomed and it was eventually cancelled in November 1997.
Neversoft shrunk to just twelve employees. The company then spent the next few months shopping around their technology, meeting with numerous companies and looking for work.
In January 1998, just as Neversoft was about to run out of money, they had a fortunate meeting with Activision who were looking for someone to re-develop Apocalypse, a failed internal project featuring the voice of Bruce Willis. The technology developed for Big Guns turned out to be ideal for the project, Activision wase impressed and Neversoft began work on Apocalypse.
In the end Big Guns / Exodus was never released, but at least its 3D engine was used for 2 other games: MDK and Apocalypse.
Thanks to Jason for the english corrections!