The decision to draw routes rather than making this another twin stick shooter is a very good one. There's an excellent metagame of deciding between drawing long routes or short tactical swipes in response to opponents' movements.
I get the impression you originally hoped to make this a level-based game, but due to time/apocalypse constraints you deferred back to the tried-and-true arcade structure. The level of damage you take from opponents attacks likely would have worked better in the former format than the latter. If the attacks did a little less, or if the enemy's shells took a little longer to reach their targets in order for you to dodge/shoot them out of the sky, the matches might last longer and might further strengthen your blend of tactics and twitch-based gameplay.