Variety reports that Robert Downey Jr. may join "Cowboys & Aliens," a project which has been in development at several studios over the past 10 years. The trade describes the film as a mix of sci-fi and western and is being aimed for a 2010 release. Dreamworks and Universal will distribute the movie.

Imagine Entertainment partners Brian Grazer and Ron Howard are producing. Platinum Studios chairman and CEO Scott Mitchell Rosenberg also will produce, along with DreamWorks' Steven Spielberg, Alex Kurtzman and Roberto Orci.

Based on a graphic novel by Fred Van Lente and Andrew Foley, the movie would tell of an Old West battle between the Apache and Western settlers, including a former Union Army gunslinger named Zeke Jackson (Downey), that is interrupted by a spaceship crashing into the prairie near Silver City, Arizona. The story "draws a parallel between the American imperialist drive to conquer the 'savage' Indians with its advanced technology and the aliens' assault on Earthlings, who must join together to survive the invaders' attack."