ElDewrito, a fan-made mod for “Halo Online,” stopped development this week after Microsoft reached out to its creators about the legality of the project, both Microsoft and members of the  ElDewrito community said.

“Halo Online” was a PC game designed exclusively for the Russian market by Microsoft, 343 Industries, and Sabre Interactive in 2014. It was put on “indefinite hold.” The ElDewrito mod lets people create player-hosted servers within the game. It also restores some removed features, fixes bugs, and adds support for other modifications.

In a post on the Halo Waypoint website, Microsoft said it’s just trying to protect its intellectual property. “While we are humbled and inspired to see the amount of passion poured into this project, the fact remains that it’s built upon Microsoft-owned assets that were never lawfully released or authorized for this purpose,” it said.

ElDewrito is different from other fan-made projects, Microsoft said. A free expansion for “Halo: Combat Evolved” on PC allows players to create and share content, for example, but it requires a valid retail key and follows Microsoft’s content usage guidelines.

“Community created content has long been a key pillar in the ‘Halo’ franchise and something we have continuously sought to support — from the early beginnings of Red vs. Blue to Forge-made maps and modes to the ‘Halo Custom Edition’ to original recent fan creations like ‘Installation 01,” it said. “These projects, and others like them, have one key factor in common — they fit within Microsoft’s established content usage guidelines.”

“With ‘Halo Online,’ there’s a common misconception that once it was canceled, the assets were either turned over as ‘open source’ or left for the community’s whims as ‘abandonware’ — neither of which is actually true,” it added. “Not only did Microsoft issue takedown notices at the time of the original leaks, but many elements of that underlying code and content are still actively being used today and will continue to be in the future.”

In a blog post, ElDewrito said Microsoft reached out regarding potential legal action and asked it to temporarily halt development. While it didn’t send an official cease and desist letter or Digital Millennium Copyright Act (DMCA) takedown, Microsoft apparently had a “brief conversation” with the team about what it could do.

“Since ElDewrito itself is simply an open source mod and not a Microsoft asset, the mod itself will not be taken down,” the team said. “However, it appears that any Microsoft assets required to play the game will likely be taken down by Microsoft. All we know is that have been told to temporarily halt development until more information is available, and we must [sic] honor this request.”

Microsoft said while the ElDewrito team is understandably upset at the outcome, given the amount of time it’s invested in the project, it understands the legal implications and the need to hit pause. The company added it reached out to the ElDewrito modders to have what it calls an “open discussion” about the project.

“As we look ahead, we’re very excited about the prospects of an official classic ‘Halo’ experience making its way to PC and we hope to be able to partner with the ElDewrito team and broader mod and content creation community to help inform the types of experiences and features our fans desire,” it said. “While we have nothing to announce today, please know that the PC community is very important to us and top of mind as we work towards the future.”