A Button: Used to jump up in the air; Hold a directional pad to commence a somersault in the air.
B Button: Fire Arm Cannons; Fire Missles; Fire with current Weapon. Lay bombs (in Morph Ball mode)
Select: Switch to Missle Mode.
Start: Pauses the Game
Left/Right: Move Samus
Down: Turn into morph ball
-[Extra Note] You'll also get energy boost while you progress through the game to increase your attack.
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