The game has the story of NES Metroid, with the gameplay and style of Super Metroid. Bounty hunter Samus Aran must research the dangerous Metroid creatures, which latch onto you and suck out your energy. On the way, there are lots of Space Pirates and other nefarious creatures to face. As you progress through the game, Samus gains new abilities, such as stronger suits, varied weapons, and more and more missiles to blow the crap out of enemies with.
Even though the game is beatable, you will still find plenty of challenge. Expect a number of large, sometimes ridiculous bosses, along with loads of wicked, often annoying enemies.
I remember when this game came out, I played it every day until I finished it. I even played it in my sleeping bag while my brother and I slept outside on the trampoline. The next day, I took a nap on the couch. Then I stood up too fast and I passed out and my hand ended up in the mop bucket. So... there ya go.
Also, I gave this game to my brother for Christmas. But I was really tricky about it. I took the game and pamphlets out of the box, collapsed the box (they were made of cardboard), and rolled everything up and put it in an empty Pringles can. Then I wrapped it up and had him try to guess what it was. In November. It was hilarious.
In any case, if you don't mind, I'll now be heading to the Planet Zebes to kick some Space Pirate tukhus. Wish me luck! Or don't, because I don't care.
*Probably none of this is true.