AD or ←→   rotate plane

W or ↑   thrust engine

SPACE   fire guns

SHIFT   dash / evade (brief invincibility)

P   pause   M   mute

Speed over the wings gives lift — fly level to cruise.
Score enough and LEVEL UP — pick an upgrade yourself.
Kills rarely also drop a bonus upgrade pickup.
Air thins with altitude — ENGINE climbs; kills up high score more.
WATER lets you skim then DIVE — but SEA MONSTERS lurk below.
Bosses roam; go deep for the LEVIATHAN, far up for the MOTHERSHIP.