What was the world's first handheld game device?

The world's first handheld game device was the Mattel Auto Race, introduced in 1976. It was a small, electronic device that featured a simple racing game where players had to navigate their car along a series of dots on a virtual track. The device had a small screen and used LED lights to display the game graphics. Despite its limited capabilities, the Mattel Auto Race paved the way for the development of more complex and advanced handheld gaming devices in the future.