With success like that, the easy thing to do with Zelda 2: The Adventure of Link would've been to simply copy the style of the original, which obviously worked very well, and replicate that in a new game. Mix up some dungeons, add a few new items, and, without too much effort, it could be almost certain to be another hit, and mount huge sales yet again. That wasn't the path that was chosen for Zelda 2, however, as the game had a very different feel from its predecessor. While it might not have been what one was expecting after having played Zelda 1, Zelda 2 is a spectacular game in its own right.
The first thing that will appear as a difference to people familiar with the style of Zelda 1 right away is, when you begin Zelda 2, you're greeted by Link standing tall on the screen, with actual height to him now, in a side-scrolling room. Link can move left and right on this screen, swing his sword and, in yet another difference, jump around to his liking. These are just the differences which are immediately apparent upon starting the game, as there are many other things that one will encounter along the way which will be different from Zelda 1, or really any of the other Zelda games that one may have played. This isn't all one big comparison of Zelda 2 to the other Zelda games though. While the other games are very good as well, Zelda 2 is an excellent game at what it does, and there's much about that to describe.
The other thing that one will notice upon starting is that, in the background, is a platform with a person lying on it; this person is Princess Zelda. It seems that, after having defeated Ganon in the previous game, he placed a curse on Zelda, and she's stuck in a state of eternal sleep (or something to that effect). So, you actually know where Zelda is in this game, you don't need to save her from being captured or anything. Just, the problem is, it's not very exciting with her just lying there. In order to remove the curse, you need to take 8 crystals that you have and place them in their proper spots. As one might imagine, however, these spots aren't just sitting out in the open; these places are hidden in palaces spread out across the land, guarded by many enemies and other obstacles. Still, you're the hero, and it's your job to deal with this sort of thing.
Once you leave the palace, you'll be greeted to a more familiar style of presentation. Outside, you're seen from an overhead view, walking around on a big map, more similar to the style of Zelda 1. The difference here being, you don't actually do any fighting or anything on this screen. Instead, as you walk around, enemies will show up on the screen and move toward you. If you come into contact with one of these enemies, you'll be transported to a battle area in a side-scrolling format again. The exact style of the area you're in depends on where you encountered the enemy: Standing on Desert, Grass, Forest or others will lead to different surroundings and the exact set of enemies you'll encounter within. Inside of this area, you're placed down in the middle of the screen. To return to the map, all you need to do is reach the edge of the screen on either the right or left. Needless to say, however, there are a number of enemies along the way who are determined to not make this an easy process for you. So, you'll either have to avoid or dispatch of these enemies on the way to the end. In order to fight off the enemies, you're equipped with your trusty sword, which you can attack and defeat the creatures you encounter.
The enemies aren't just there to get in the way, however, as defeating them leads to another difference about this game: Experience points. Defeating most of the enemies that you encounter will give you a certain amount of experience points, which will become higher as the enemies get more challenging and you progress further in the game. You can also occasionally find "bags" of experience hidden in certain areas, which will give you a bunch of bonus experience. These experience points are saved up toward a total, and when you reach the goal for the total, you'll be able to use it to expand one of three powers: Attack, Health and Magic. Increasing these won't actually increase the meter (in the case of Health and Magic which both have a meter), but instead will cause you to take less damage and for your spells to use up less magic. Each of these three categories has 8 levels, and as one moves up to the higher levels, the goals one has to reach to attain them will move up as well.
Another new thing in this game is the addition of magic spells. You don't start off with any, but, as you’re walking around talking to people (more on that later) you'll encounter people in different places who will give you a new spell. Some of these serve the purpose of healing or protecting you, while others grant you power such as a reflective shield or the ability to shoot fireballs out of your sword which will actually come into play as they are required to defeat certain enemies and levels. Another thing that enemies will occasionally leave behind aside from experience points is a magic bottle which you can get to fill back up some of your magic meter. So, you can make use of your different magic spells for an assortment of situations to help you get through things or to make things easier and more manageable for you.
The other big change in this game is that, you aren't just working your way through an overworld and dungeons; there are towns to explore as well. These towns, in a side-scrolling area similar to the battles, have people who are wandering about who you can talk with to get clues and hints. While the dialog may not be the most captivating thing in the world, it's still definitely more involved than the rare snippet which one encountered in the previous game. So, although you may not be reading a novel while talking to these people, it's still very interesting to be able to gather information about various things this way.
Once you've gotten all these changes under control, it's then time to tackle the actual problem of helping the princess. Like Zelda 1, Zelda 2 also makes use of a battery to store your save. While you'll find yourself back at that initial area every time you start, at least your progress and the things that you've done so far are saved. From the beginning area, you slowly begin to work your way outward, limited not just by the enemies, but by certain areas you can't reach and certain things you can't do until you have particular spells and items. Following the path that you can take, however, will lead you to the first palace. Here, you'll fight your way through a number of different enemies, get an item which will help you on your way, and at the end come to a boss guarding the area you need to reach. After taking care of him, you'll be able to go replace one of your crystals, getting closer helping to restore Zelda.
As you get more items and spells and such, the area you can explore will increase, and the world will start to open up. As you get different abilities you'll be able to take various shortcuts (such as just breaking through a rock as opposed to having to take a long path around it) which will make your journey a bit quicker in returning to where you had been before. Still, it can often be quite the hike back to where you had last been playing. As you explore the land, you'll discover many different areas and places which you'll have the opportunity to explore, from towns and forests to graveyards and areas filled with lava. The landscape of the overworld map, and the various areas you'll discover in them, are quite varied and interesting.
The palaces themselves often look quite similar in construction, with just a simple change to the color of the walls to give things a different appearance. Still, it's not as if the later ones are going to be just as easy to go through as the first ones, as the size and complexity of the areas that make them up definitely increase. Also, you'll have to make use of the various items and spells that you get in the course of your journey, not just in getting to the palace in the first place, but in different ways to approach and explore things which you wouldn't have been able to do before. As well, the enemies you'll encounter in the palaces, both the end enemies and just the assorted enemies you run into on the way through, are quite interesting, with a large variety to them as well. So, there are many things that you will see on your journey which will keep things new and interesting.
As mentioned with the palaces, the actual makeup to the look of them often isn't too interesting, usually just a fairly plain colored wall surrounding the areas. There will be various pillars and blocks and such which will liven up the areas you're walking through, and everything does look nice enough, but, nothing too exciting. The towns are fairly interesting, with the houses, both inside and out, being rather detailed. The insides of the buildings in particular are often very interesting and fun to explore. Also, although there are only a few different character pictures used for the people you'll encounter in the towns (how many tall thin women with a bowl on their head are there wandering around this place?), they all do look fine as well. With the music in the game, there isn't too much variety to it, but, all of the various songs that it does have sound nice, and fit the areas where they're present very well.
In this game, like many other games with various experience/level systems and such, one will probably spend a decent amount of time wandering around fighting stuff just for the experience. Of course, one isn't required to do this, but, if definitely makes things easier if you can kill a particular enemy in 2 hits instead of 10, and cast more than a couple of spells before running out of magic. While you don't have to get the statistics up to maximum or anything, the more time one puts into it and the higher one gets them, the easier things will be. Likewise with the heart and magic containers to expand one's maximum that are scattered around the land, while one doesn't have to find all of them, it will definitely make things easier to have more of them. Usually they're in obvious enough places, just, sometimes it requires a bit of extra work to get to them. For instance, there may be a cave off to the side, where the only reason to go into the cave is to get a container. So, it wouldn't always be something you'd just pass by on your way to somewhere else you needed to go, but, the locations where one does have to go usually stand out well enough.
All of this work one can choose to put into the experience, spells and life/magic containers will definitely be worth it though, since this is also a rather challenging game. Not to say it's going to cause one to get overly frustrated and turn the system off and storm away, but, it's quite likely one is going to die a good amount, and get all too familiar with being back at that beginning area and having to retrace one's steps. Still, it's nice to have a game to provide a challenge, and this game definitely does do that. So, while it may take a bit more work than one is used to, it's definitely worth the effort.
Once one has beaten the game, there are a number of reasons that one might choose to play through it again. The first, of course, is simply because it's fun and one wants to do it again. Also, if one didn't get as many levels as one could, or find all the life and magic containers and such, one can go back through looking for those as well. There are definitely a number of things that one might not have done the first time through, which one can go through again looking for them. As well, if one didn't take too much time out stopping to talk to the people and explore the towns, that can be quite enjoyable. They're not going to tell you any epic stories or anything, but, they're still fun to listen to. One might not have gone to every side area or explored every corner of all the palaces, so, there can be that to go back for as well, seeing everything there is to do. Then, the game also keeps a record of how many times one has died, so, one can also go through again with the challenge of dying less often than one had originally. So, while there aren't any hidden "unlockables" or anything like that to specifically entice one to go back through again after the game has been beaten, there are definitely a number of fun things that one can still see and do in the game that one might not have done the first time.
It may not be exactly what you're expecting from a Zelda game, especially if one has already played some of the other games in the series and is used to that style. Certain things from this game have made their way into the Zelda series and stuck around in one form or another. For the most part though, it's quite the different game; still, that definitely doesn't mean it's a bad game. Whether one is specifically comparing it against the other Zelda games, or any other type of game in general, Zelda 2 stands on its own as a spectacular adventure. Worth at least checking out to see if the style appeals to you, and it's something which can quite easily grab someone and pull them in, making them fall in love with it.