I love the concept of this
I love the concept of this, it has a lot of potential!
But you should definatly remake this outside of any contests or jams. I think the quality of things from contests and jams is usually pretty low, while the idea can be pretty good, since it's unfinished, rushed, etc.... That's also the case here.
But the idea is superb! What a nice way to learn morse!
Here are some suggestions:
-use letters instead of numbers to select enemies. The numbers are too long to enter.
-make the long tone shorter. In movies, long tones of morse code are shorter than the long tones required in this game. Sometimes I intend a long tone but it interprets it as a short tone.
-as others said, if there's one enemy, don't require selecting it with a number at all.
-have a working store
-allow assigning levels to defense and attack and such yourself
-longer game, more maps, more enemy types, more variation, ...