Intercept

OOP System: Projectile class with velocity and lifetime properties with a child class Missile that adds extra acceleration and rotate to the target on top of the parent Projectile properties
Audio system: weapon firing sound, hit audio, drone engine sound with doppler effect
3D: the game is made in 3D :P, bullet and drone movement in 3D, propeller spin
UI/UX: range indicator, crosshair, hit icon, simple UI scaling
Raycast: projectile/missile hit registry uses RayCast3D, range indicator uses RayCast3D to know the range

v2.0:

Save & Load: a simple score saving mechanism
Procedural Generation: the enemy wave is generated at runtime, spawning slowly.
Advanced physics for bullets lead calculation 
Simple animation for drone rotor and radar dish

Want to add but didn't manage to:

Lead prediction that accounts for target speed, acceleration, angular speed, and angular acceleration. Scrapped due to not enough time and I can't derive the general equation :(
A crude lead prediction exists in v2.0

I also wanted to implement a missile that didn't rotate immediately but not enough time too

Btw LMB to fire gun, MMB to fire missile, E to lock the target. Happy hunting!