Great stuff overall, Managed to get to level 25. Experimenting with the order of units you can send out to try to get as many lives as possible is quite enjoyable. Shooting is decent, though later on you can get a reliable level clear by staying in one spot, should def sprinkle in more movement pattern variety.
Some bugs here and there but quite clean. The arts okay but could be better, I like the spaceship sprites. Would be leagues better if the artstyle was more consistent overall though