This is a good use of the theme. I had some knowledge from morse code, but it feels really stuck in my brain now.
I got addicted. My highscore is all correct in exactly 50 second on hard. Still I only got 90 survivours?! Is is possible to get more?
The only one thing missing was a restart command. It could have been"dit dat dit dat dit" - which is the code for the end of the message.
Great educational game. I don't know what I will use morse for but hey I know it now :D.