This game's actually pretty fun, and while the mechanics are pretty simple they are also pretty deep in their strategy. I can easily see how this could become a great game with the features you're developing right now!
That being said, I had a few issues, mainly for me it was the mouse controls, which I found to be a bit unintuitive. My problem was that I clicked on an island to select that island, but the selection doesn't reset so I accidentally sent other island's planes too, quite a few times.
Other than that the random level generation could be cool, but I got put in a pretty unfair spot at the start of one round and died pretty quickly, which sucked because it didn't feel like I could do much about it. And on another round I got put in a really good position and felt a bit bored. But that's balancing, which you're going to address anyway.
Anyway, aside from that I really like the art and sound, menu was a bit loud, but a good game over all. Wish you luck for this project!