Activision Inc. said Wednesday that it has agreed to acquire U.K.-based developer Bizarre Creations in an effort to diversify its game titles.

The Santa Monica-based game developer and maker of the wildly popular “Guitar Hero” franchise bought the British company to add car-racing titles to its library. Bizarre developed the “Project Gotham Racing” series for Microsoft Corp.’s Xbox consoles, with another title due to be released in 2009.

Activision said that adding racing titles, which are less-complicated than traditional games, will attract more casual players to video gaming. Racing titles are the fourth-most-popular genre of games, Activision said. Financial terms of the deal were not disclosed.