Children can experience incredible augmented reality gameplay with the LEGO Hidden Side "Ghost Train" (70421) playset. This fantastic playset, complete with an app for kids, combines a buildable LEGO model with an augmented reality experience, providing a fully interactive gaming experience. Download the Hidden Side app and scan the model with your smartphone to bring it to life – playing with the model triggers events in the app. Continuous updates, a unique ghost boss to defeat for each set, and always new puzzles, items, and ghosts to collect – the LEGO Hidden Side set opens up entirely new possibilities for kids when playing with LEGO bricks! The amazing train playset features cool high-tech ghost-hunting details for hours of imaginative play. The 5 minifigures, including Jack and Parker, offer endless play possibilities – the fun can start right away!.