Holy moly, this is awesome. How something like this can be created in 4 days absolutely blows my mind. This is basically an entire game.
It also reminded me of the times when I used to play Empire Earth as a kid with my cousin. The upscaling even feels like the evolution in that game too! Thanks for reminding me of that! For a jam game, this is brilliant. Even if it wouldnt be a game jam game. STLL BRILLIANT!
PS: I also really love the personality of the radio guy in the tutorial. He's an ass, but still, haha.
The only criticism I have is that the own units sometimes feel a lot weaker. Two units of the same size could destroy eight of my eagles. Probably because the homing is slow compared to direct shots.
Besides that, this is a super cool game and a really unique idea. Good job!