Shares of Zynga, the "Words With Friends" game maker, at last check were down 1.9% at $11.18.
Terms were not disclosed and the acquisition isn’t expected to be material to Zynga. Both companies are based in San Francisco.
The agreement comes at a time when gaming's popularity has surged as people stay home due to the coronavirus pandemic.
In a statement Zynga said the acquisition of Echtra Games, maker of such titles as "Diablo," "Diablo II" and the "Torchlight" franchise, will bring in a development team with extensive cross-platform experience.
The Echtra Games team also offers proprietary cross-platform development tools and technologies that have been built on top of the Unreal Engine. That's a game engine developed by Epic Games and first showcased in the 1998 first-person shooter game "Unreal," Zynga said.
The Echtra Games team will be developing a new, yet to be announced role-playing-game for cross-platform play with Zynga’s NaturalMotion studio.
Echtra Games was founded in 2016 by Max Schaefer, who was also one of the founders of Runic Games. The company has about 50 employees.
Zynga will release its first cross-platform product -- "Star Wars: Hunters for the Nintendo Switch" -- later this year, and other titles are in the works, according to Bloomberg.
"Max and his team at Echtra Games are responsible for some of the most legendary game properties ever created, and they are experts in the action RPG genre and cross-platform development," Zynga Chief Executive Frank Gibeau said in a statement.
Last month, several analysts upgraded Zynga after the company released its fourth-quarter results.
Zynga reported a doubling of monthly active users to 134 million as people spent more time on their phones amid the coronavirus pandemic and lockdown.
In June, Zynga said it had agreed to acquire "Toon Blast" and "Toy Blast" mobile-game maker Peak for $1.8 billion in cash and stock. In October, the company acquired Rollic, the Istanbul mobile-games developer and publisher.