Xbox Entertainment Studios is deep in negotiations with Showtime to develop a live-action “Halo” drama series that is a high priority for the Microsoft production unit headed by Nancy Tellem. Xbox Studios has been developing a drama series spin on the vidgame franchise with Steven Spielberg’s Amblin TV banner for more than a year. It’s understood that the company is close to a deal with a pair of showrunners to steer the series adaptation of the expansive bible developed by screenwriter Stuart Beattie, but the deal is not envisioned as a straight-to-series pickup. Xbox aims to develop “Halo” and other properties as high-end series productions in an effort to enhance the Xbox platform as an entertainment service for its base of 48 million subscribers. The deal with Showtime has taken a long time to work out because the sides are charting new territory for a show designed to air on Showtime as well as Xbox, with enhanced interactivity built in for the latter platform.