MTV Networks’ Nickelodeon will spend $100 million over the next two years to develop online games aimed at children as it seeks to tap a fast-growing part of the $30 billion industry.

The investment will pay for a slew of new subscription services, multiplayer games and virtual worlds for kids.

Eyed by many game developers as one of the fastest-growing segments of the business, so-called casual games are those such as puzzles or card games that can be played for just a few minutes or on the run.

Usually featuring simple graphics and controls, casual games have helped the industry expand its audience beyond the young male base that is more interested in games featuring graphic-laden gore and guns.

The division of media conglomerate Viacom Inc. said it will introduce several new online products in 2008 to 2009.