Really fun game. It's really satisfying when you manage to hit a big attack, and I can see myself playing it again later.
The shields, though, could be improved: they recharge pretty fast, so you can't wait too long to attack, but if you don't wait long enough your Attack command will not reach many ships. I understand the risk/reward here (and the need to make EMPs relevant), but it doesn't feel quite balanced yet. Also, they could have a little timer showing when they will activate again.
Another suggestion is a Cancel command, so you can cancel (obviously) a misclicked/wrong order. Then again, properly choosing orders is part of the challenge.