Toppling Steam will not be easy. Changing the habits of entrenched users can be difficult, and even companies with large audiences have struggled in the digital distribution space. Twitch, the streaming service owned by Amazon, and Discord, the chat program used by many gamers, recently shuttered their public storefronts.

But there has been growing frustration within the industry about what some call a glut of games on Steam — it offers more than 30,000, while the Epic Games Store has curated fewer than 100 — and an antiquated revenue-sharing model that benefits Valve.

Epic is already off to a strong start. It has greater access to China’s lucrative market, with more than 300 million computer gamers, through its investor Tencent. That company paid $330 million for 40 percent of Epic in June 2012, years before Fortnite became a global phenomenon, in a deal that valued the company at about $800 million.

To court developers, it has promised to keep only 12 percent of game revenue, less than half of what Steam keeps. And it waives the 5 percent royalty fees for games built using its Unreal Engine, a suite of design tools used by developers.

Many publishers and developers of computer games, large and small, are eager to do business on the new platform.

For years, Ubisoft released blockbuster titles like Assassin’s Creed and Splinter Cell on Steam. But it decided not to sell the sequel to its hit game Tom Clancy’s The Division on the platform because Valve would not modify its revenue-sharing model, said Chris Early, Ubisoft’s vice president for partnerships and revenue. The game is for sale on the Epic Games Store and Uplay, Ubisoft’s store.

The move was part of a broader business discussion at Ubisoft about releasing titles on Steam, Mr. Early said. “It’s unrealistic, the current business model that they have,” he said. “It doesn’t reflect where the world is today in terms of game distribution.”