Go Crash Course is a free application available for Android users designed by AA Mobile. This app is an excellent resource for anyone interested in learning the game of Go. It offers more than 20,000 Go questions and covers a wide range of topics, including Connect, Geta, Bridge Under, Sagari, Placement, Jump, Under the Stones, Sekito Shibori, Attack, Blind Spot, Crane's Nest, Shaping, Tripod Group, J Group, Carpenter's Square, Shape, Life and Death, Tesuji, and Composite Training.

The app is user-friendly and easy to navigate, making it an excellent choice for beginners. The questions are well-organized and provide a comprehensive learning experience. The app offers a variety of features, including a timer and hints to help users improve their skills. Moreover, the app is free, making it accessible to anyone who wants to learn Go. Overall, Go Crash Course is a great app for anyone looking to learn the game of Go, and I highly recommend it.