I found myself compelled to not quit until my score was 100% and even though it was stressful, it was very enjoyable. Its nice that the gameplay strategy isn't linear since the player can choose to prioritize new skills, multiple lower tier enemies or even a quick Tier 3 enemies to progress faster. Can't think of much improvements other than it seems that shooting the fans when very close to the enemy fan seems to not do anything.
Lots of fun, good job!