Music 
SketchyLogic
https://opengameart.org/content/nes-shooter-music-5-tracks-3-jingles

Afterburner Sound
dklon
https://opengameart.org/content/jet-engine-takeoff

Gun Sound
KuraiWolf
https://opengameart.org/content/light-machine-gun

Explosion Sound
Michel Baradari
(Submitted by qubodup)
https://opengameart.org/content/2-high-quality-explosions
