verall graphics sound addictiveness story depth: difficulties
The game on the Nintendo Entertainment System was I believe one of their adventure series of games when the system was first starting out, and as amazing as this game is, a lot of what makes it great is very commonplace nowadays and so in some ways Metroid might look sketchy from a modern prospective  particularly when you take into account the game has some annoying aspects, so to look past the Flaws and appreciate the good in the game it helps to have a historical perspective and keep in mind all the cool things the game does that the game was kind of the first to do.  Also it helps to be patient because the game is best moments are deep in the game and at the end of the game so the game really starts you out with more of the mundane stuff like the critters the crawl along the walls and everything.  But I'm getting ahead of myself.
Metroid is this side- scrolling non-linear action adventure games set in a spooky scifi universe whercreepy are completely alone except for creepy critters and evil monster space pirate alien things.  The protagonist is very noteworthy because of this crazy twist ending that you learn about them that by now Nintendo fans probably already know but at the time this game came out all you really knew is that it's a mysterious bounty hunter character with a suit of armor and arm cannon and they can shoot missiles an upgrade their fire power and morph into this little ball that drops bombs which is really freaky and weird an innovative.  At the time, being able to progress not just left to right but then right to left and UP and DOWN was kind of a big deal.  
Graphics
The graphics in Metroid a good because the main character animates very well there's a great variety of creepy crawly critters and monsters and evil space pirates but even more than that the best part about the graphics is that the diversity of settings some of them pretty creepy help to keep things interesting, they mark the territory so its clear when you are in a new neighborhood, and the setting really establishes the creepy sci fi atmosphere with lava pits teeming with fire breathing monsters and such.
Sound the sound in Metroid is amazing, this sound effects are numerous and everything you do has an awesome sound effect to go along with it that sounds appropriate to what it should be and even actions that you would think might have an annoying sound effects like the ScrewAttack that happen all the time, even those actions are accompanied with a sound effects that does not get old or annoying it actually sounds cool everytime you hear it so that's good sound effects design. The music is completely amazing the soundtrack by the legendary hip Tanaka has been remix 10 remix to this day, the musical tracks are spooky and atmospheric and even things like teleporting into existence in the beginning of the game or everytime you find an item there is just the coolest atmospheric little tune iconic is the word you would use to describe it, the music in this game is great, and it's important that the music is great because when you're just wandering around the atmosphere is very vital.
Addictive miss
This game is very addictive, the unknown the exploration diving into the abyss it's all very fun and in order to power up your character and fight the secrets especially if you don't cheat and just go straight to all the cool stuff is very rewarding to look in every nook and cranny undefined a secret passageway end with to be rewarded with one of the coolest items in the game. I don't want to get flat spoilers but the best items in this game are hidden behind not one but off in like 2 or 3 secret passageways so you have to find them all to leave your way to the hidden corners of the game where the best stuff is.
This is a good section to talk about one of the annoying part of the game, which is that it's very unforgiving if you become low on stuff there is no way to instantly get full missiles or full energy so if you are unfortunate enough to die or use your missiles for example on the enemy's who did not die unless you hit them with a lot of power such as a missile you may find yourself in a position torn between do I fight enemies over and over and grind for power ups and recharge my huge number of missiles to a time in a very boring get away or do you just quit the game and start over from scratch because sometimes it feels like either would be equally quick it's ridiculous how slow it is to grind and get items and that's why in the sequels to this there are statins where you can recharge your energy and recharge your missiles and if there was some kind of feature like that it would have been good especially since the only way to get a password is to kill yourself so unless you're going to leave the game running for long periods of time, you're going to have to grind her energy or missiles because you'll have to deliberately kill yourself if you want to get a password simple as that. This is one of the aspects of the game that has an age so well it's really a flaw in the game design in my humble opinion.
Story
The story of this game is pretty bare bones not too many plot development say anything but I would say that the story is still good because it sets up the atmosphere and in some ways finding new locations new enemies new space pirates qualifies as a plot twist or plot development so in the way that video games can tell stories nonverbally just showing this creepy adventure of this science fiction hero person I'd say the story is solid but by modern standards they could have thrown in some more crap although be careful what you wish for because some people complain when they talk your ear off and games like Metroid Fusion on the Gameboy Advance, if you're looking for more story by all means check out one of the sequel such as that one.
Depth difficulty
The depth of difficulty of this game go hand in hand both are great isady because the more you explore and go into the depths of the game the easier the game becomes because your character gets more powered up you learn to lay out if you're smart you might make a map in less you have a really good memory for where everything is so I'd say that the Dept is very good it's very deep and once you beat the game you have the option of going back to get a better ending they always want you to speed up your time dad speed X if you see a speed right of this game is amazing because it's really challenging to try to beat yourself to get innovative ideas okay what route do I take this the fastest to beat this game it's very rewarding to try to beat your time and the final battle is pretty difficult just surviving it is quite a challenge too.
In sum, check out this great sci fi classic or one of its many sequels on vizzed!!