You've done an excellent job with this one! I'm standing up while playing and found myself subconciously tapping my foot in time with the music as I captured drones, was really getting into it!
I played in Chrome and unfortunately hit the same error message as DouckDouck did, it happened right after I successfully captured a drone at one point.
My sole piece of feedback would be to have a more obvious visualiation of the drones being spawned/captured. As best I can tell, there will always be 4 drones on screen (at least, as far as I progressed). When I captured my first few drones, I was confused when the camera zoomed back out and it was always the same number visible as before. At first I took this to mean that the drones had health bars and I needed to perform multiple actions on individual drones, not recognising the bar represented their time left until escaping, not a health bar as I assumed.
Perhaps either a capture animation, or else waiting a moment after a uccessful capture to obviously spawn a new drone into the area would help remove that potential confusion!