Epic Games, the videogame maker that started a daring legal brawl with Apple last week, is hoping to organize wider opposition to the tech giant. It could face an uphill battle in recruiting others to publicly join its cause. 

In recent weeks, Epic—which makes the hit game Fortnite—has reached out to other tech executives about forming a coalition of companies critical of Apple’s business conduct, including its policies governing the distribution of mobile apps on its mobile platform, iOS, according to four people with knowledge of the matter.

Epic has recently had preliminary discussions about the coalition with music streaming company Spotify, another well-known critic of Apple’s business practices, but the music-streaming company hadn’t yet signed on to join it as of last week, one of those people said. The game maker also approached Sonos, the maker of connected stereo equipment, which is considering joining the group, another one of the people said.