Metroid HD: Korea Subway Info is a free Android application that provides users with the latest and most detailed information about the Korean subway system. This app provides a high definition feature that is compatible with the high definition route map. Users can also access the latest timetable through OTA updates and get detailed and optimal path information, including express trains.

The app also offers a full touch-based feature, providing users with the latest and detailed information about every station. It supports six languages, including English, Korean, Japanese, Chinese, Indonesian, and Malay. Additionally, users can get various information such as arrival time, each station's full timetable, Google map, and detailed path information.

One of the recent updates includes a reverse search feature, and the path search feature now includes the whole express trains. Users can also zoom in/out easily using the HD route map feature. The app is compatible with JB+/Kitkat devices and is updated whenever a new line starts operation.

Overall, Metroid HD: Korea Subway Info is a useful and informative app for anyone who uses the Korean subway system.