Red Entertainment
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At Sega's Game Jam II showcase in March 2002, Red Entertainment announced two new PlayStation 2 games in collaboration with mangaka Yasuhiro Nightow that would be published by Sega, who had also announced a 67% stake in the company moments prior. The first game announced was Gungrave, which was released in Japan in July of that year. The second game announced was a game based on Nightow's 1995 manga "Trigun" entitled "Trigun: The Planet Gunsmoke", with a short 20 second teaser trailer being revealed featuring silhouettes of multiple characters from the series before ending on Nicholas punching the screen and revealing the game's logo.

Since then, the game has become vaporware as no other updates from either Red Entertainment, Nightow, or Sega have been released about it since its announcement, with the exception of an official statement from Sega on the game's development that read "no comment". Fans have since speculated that Gungrave actually is a modified version of Trigun: The Planet Gunsmoke citing its similar storylines and character designs to that of Trigun, but considering both games were shown off at the same time and Gungrave was released in Japan only four months later, this is unlikely.
Contributed by MehDeletingLater