The metroid series is an amount of games where you are Samus Aran a bounty hunter traveling around the universe in the varia suit. The varia suit simply has a power beam on the right hand (kind of like a gun) and you can get updates on your suit such as dark beam, light beam, dark suit, PED suit, PED plasma rifle, morph ball, missiles, gravity suit, etc. You kill aliens and try to defeat the different storylines.
GAME #1: You return to the Chozo planet to destroy the space pirate mothership and to visit some of your old friends, THE chozo. When you arrive on their planet they are gone and you try and figure out the reason for this.
GAME#2 while following the remaining space pirates you stumble into the luminoth leader who is in a battle between light and darkness. You help him save his people and planet.
GAME#3 After returning to the military bounty hunter squad, you get attacked by the last of the space pirates and travel to different planets trying to end this war and save your endangered friends.

There are many other games in this series but these three right now are my favorite.