I have to be honest, when I played this game for the first time I didn't know what to do and just flew around till I got bored. It's really great that you read the user reviews and updated your author comments with more information and hints, and that you added a navigation system to the game.
With this few changes it's much clearer for the players what to do. Now it's an enjoyable game (yet challenging, like you wrote) with an amusing theme and good-working game mechanics.
Especially the old-school feeling of your game made it a great fun to play for me :)