UPDATE

Released version 1.1 which features the following changes.

-Added two new enemy types.

-Added a  powerup that repairs your plane increasing your health.

-Added SFX for destroying enemies.

-Fixed an issue that caused all difficulties to be equal.

-Now enemies have different speeds and shoot at different distances.

-When the game is paused, now you can resume pressing the Esc button.

-Performance improved.

-Small bug fixes.