Steven Kane (TNT's 'The Last Ship') will serve alongside Kyle Killen on the live-action take on the video game.

Showtime's long-gestating Halo TV series is adding a second showrunner.

Steven Kane (The Last Ship, The Closer) has boarded the live-action drama as co-showrunner. In his new role, Kane will serve alongside showrunner Kyle Killen (Lone Star, Awake).

Sources say the decision to bring in a second showrunner came directly from Killen, who wanted to focus on the big-budget project's stateside production — including writing and producing — as he sought a partner who was able to spend the better part of a year in Budapest during physical production on Halo. Killen is expected to be on set but not full time. Showtime, in announcing the series pickup last June, called Halo its "most ambitious series ever."

In its series order release, Killen was attached to serve as the lone showrunner on what was a 10-episode live-action scripted drama. Since then, director Rupert Wyatt departed (citing scheduling conflicts with an unknown other project). Wyatt was poised to helm multiple episodes and serve as an executive producer on the series from Showtime, Microsoft/343 Industries and Amblin Television. He was replaced by Otto Bathurst (Black Mirror), and an episode was shaved off of Halo's initial order.

Casting and a production start date have not yet been determined.

For his part, Kane co-created and served as showrunner on TNT's Navy drama The Last Ship and counts The Closer, Major Crimes, Alias, NCIS, Without a Trace and American Dad among his credits. He is repped by WME and Rain Management Group.

The Halo TV series was first unveiled in 2014, with Xbox Entertainment Studios nearing a deal to develop the take on its wildly popular video game. At the time, the plan called for the effort to bow first on Showtime before moving to Xbox consoles. It is unclear if that is still in the cards. The Halo video game franchise has sold more than 77 million copies worldwide and grossed more than $5 billion in sales.

The Showtime series will take place in the same universe that launched in 2001 and will dramatize an epic 26th century conflict between humanity and an alien threat known as the Covenant. Halo will weave deeply drawn personal stories with action, adventure and a richly imagined vision of the future, Showtime said. A casting notice obtained by The Hollywood Reporter confirmed that the series would feature a live-action version of John/Master Chief, whose face is never fully shown in the games. Instead, the character — an imposing, genetically enhanced supersoldier — is almost exclusively seen in his iconic green armor and helmet.