東京都 地下鉄 is a simple simulator ( シミュレータ ) of the Tokyo Yamanote Line (山手線). I wanted to use the eki (駅) jingles in a game. There are options to toggle the map and toggle displaying the eki (駅) names. This was my first time using multiple viewports in a game. There is an overhead view showing the entire line, and a smaller window showing a closeup of the densha (電車).