Thanks for the suggestions. I'll think about it, while keeping in mind that I don't want the game to become (too) complex. The routes are just an extra option besides the usual vectors, therefore I kept the routes in a simplified form like most other features in the sim really. The file format could have been more consistent in hindsight, but it's not worth changing it.
The game can be played with just mouse and keyboard commands; see the manual.pdf for all available commands. The distance from a selected plane to the mouse position is displayed at the bottom of the screen.