Great presentation and sound, it could use with more strategy perhaps? definitely feels like zigzagging as mentioned below - what if different enemies had different sides to receive dmg? Perhaps red enemies require hits from their sides so you have to move the bullet into them horizontally, or vertically for other enemy types? This in turn would move you differently adding to the challenge of negating dmg while you inflict it. Either way very well made in such a short time, great work!