Microsoft is to allow the developer of Xbox game Halo 3 to become an independent company.

The developer, Bungie Studios, set a sales record when it released Halo 3 on 25 September. The video game took $170m in its first 24 hours. Microsoft will retain an undisclosed equity interest in Bungie.

Before its association with Microsoft, Bungie was a legend on the Mac platform. The games-development firm was behind Marathon and the popular Myth series, with Pathways Into Darkness and early Mac-only first-person shooter games.

Frank O'Connor, writing lead at Bungie, said the move was "fiscally prudent" for Bungie. He said the firm will get a better share of profits while continuing to work closely with Microsoft on developing games for the Xbox console. Meanwhile, he added, "practically speaking not much will change."

He left open the answer to a burning question from fans of other gaming platforms: will Bungie write games for non-Xbox consoles? "In theory, yes," he said. However, he said the relatively small staff of 120 will continue to work on Xbox 360 games for the foreseeable future. He revealed that projects for the midterm are already lined up - and all are based on the Microsoft console.

"Honestly, we're really happy working on the 360," he said. "It's our platform of choice."

But this may change - independence could lead to Bungie developing for new platforms, according to a report on MacCentral. Brian Jarrard, franchising director at Bungie, said: "Although we have no announcements to make at this time, we don't rule anything out going forward.

"But sure, now that we're branching off and controlling our destiny, that puts us in a position where we could put ourselves back on the [Mac] platform definitively again."

Bungie was once an independent company. Not quite 10 years ago it was acquired by Take 2 Interactive Software. Later, Microsoft took a share in Bungie and then bought it outright.

Microsoft owns the intellectual property for Halo, a series that recently released its third and final game, Halo 3. When Halo 3 was released it took $170m in sales on its first day, and $300m around the world over its first week. Microsoft called it the best video game and entertainment launch in history. More than 20m copies of the three Halo games have been sold worldwide.