Halo: Combat Evolved Anniversary campaign developer Saber Interactive says it was "definitely" its technology the persuaded Microsoft to partner with the studio on the forthcoming update.
Speaking to CVG, CEO Matthew Karch said his studio realises how important the Halo project is to fans and claims the Saber team has gone "all in" on making the game a success.
"It was definitely our technology and the solution we came up with [that persuaded Microsoft]," he said. "One of the things Microsoft said is they needed the gameplay to be exact. Halo fans are extremely exacting and the gameplay couldn't be changed.
"We came up with a way to do that and preserve the gameplay. I think we've mentioned this and it's public but we took the Bungie engine and we plugged it into ours, so the game itself is running in the original Bungie code but the rendering of the world and the engine is ours, so we basically took the game scripting and AI and plugged it in.
He explained: "If you drew a circle you can picture the original Bungie engine fully within the circle of our engine, almost like a wrapper. My partner Andre came up with that idea, we gave them a demo very quickly and said 'hey look, you can toggle'.
"That's something that Dan Ayoub from Microsoft really wanted, the toggle feature; he wanted to switch between classic and new. We showed them that and they we're like 'holy shit, ok'."
Karch added that he hopes Saber's work on Combat Evolved will help give the studio more credibility and raise the profile of its other shooter Inversion.
"We've had the opportunity to work with some really smart people, to work on a really big franchise which has been great.
"It's given us more visibility which we need and one of the things that excites us the most is that it's got such as huge fanbase and there's something really great about working on a property that already has a built-in community."
For more, read the full Halo: Combat Evolved Anniversary interview.