Navigating in Mikkoku is rather straight-forward - you can use the arrow keys on your keyboard to move in four directions (up, down, left or right).
The enter key serves a large number of purposes. First, enter is the key you have to press to select or decide something, like when you're navigating through menus. Secondly, you have to use enter to talk to people in-game, to examine objects and to open treasure chests. Enter is also used to board a ship or any other vehicle when standing next to it on the world map. Whenever you're stuck in the game, pressing the enter key can usually help you out.
Escape is primarily used to cancel things - for instance, when you want to exit a menu or when you want to re-select your command in combat. In addition, escape is also used to bring up the main menu whenever you're not in battle and there's no event taking place. (More on the features of the main menu later.)