Hey this is awesome! Very polished.
I know this is for a game jam but if you continue developing this, I recommend changing the main body (the circle) so that it stands out easier when you've got a lot of drones. I had a large fleet and was having trouble finding where the circle was. Perhaps making it have a different color like light green or something.
Another is to set a cap on max sounds playing. With lots of upgrades in the rate of fire + a large fleet, holding down the fire button spams the "fire" sfx too much and gets very very loud.
Late game, when you've got a lot of upgrades + large fleet, it shakes the screen a ton and lags the game until you stop firing. Can't really do much about the lag though.
But yeah, great work! And I hope you continue to develop awesome games!