My personal favorite Nintendo game, it has quite some varied gameplay: the bottom screen represents a 'dungeon' which you have to pass multiple times before you reach the dragon, the end-of-level boss, at the top screen. You pass a dungeon by killing the guard that stands on the right side, you use your sword to hit him, but you can only hit him when you stand to the far right, also the guard occasionally takes a step back so that you can't hit him at all. All this time there is a skeleton beneath you which matches your horizontal moves and stabs you when he feels like it, visible by his arm slowly moving up, which gives you time to take cover, because the skeleton doesn't move while he's stabbing.
The guard on the right dies when his energy points have run out which
are indicated at the bottom right. The guard shoots arrows at you which
automatically bounce of your shield when you are not pressing the attack
button. When you press the attack button your sword stabs to the right
and your shield moves to the left leaving you vulnarable to the guard's
arrows. Every time you're hit a heart is substracted but the game continues
at the same point. After you've killed the guard you can be awarded a number
of things: nothing, a heart, a bottle with the water of life, a tomahawk
or a map. A heart gives you another heart obviously, the water of life
can be used at any one time by pressing down, and fills your hearts to
the maximum of five although you start the game with only three.The map
reveals the shortest path through the dungeons on the top screen, the tomahawk
allows you to do considerable more damage to the dragon later on. When
you proceed through the dungeons, the number of skeletons may increase
with a maximum of four (in which case they can't move anymore)
also a ghost may appear on the left side, who shoots at you as well,
which forces you to press the attack button because that causes your shield
to be held to the left.
A helpful feature comes in play as long as you can manage to hold on to your five hearts (this can only be accomplished later on in the game) you will be able to throw your sword to the guard, in which case you can kill him without having to stand all the way to the right. Sometimes when you kill a guard and are able to continue to the next dungeon you will be given the option to choose which stairs you wish to take, the one to the upper left or right dungeon, the path is shown in the top screen, provided you have found the map.
When you have found the right path to the dragon you will be transferred to the top screen where you can only stand in two positions. The dragon breaths fireballs at you which can hit you in either position, he also swings his tail at you, but you can only be hit when you stand in the position to the right. You now have to hit the dragon until its energy points are drained which you can only do when you stand to the right, a process that takes a lot less time when you have found the tomahawk. Once you've killed the dragon you'll be rewarded a triangle (Triforce) which will appear on the left of the top screen, now you have to repeat the whole process until you've won 8 triangles after which the wall in the top left corner will dissappear and you will be reunited with your princess.
This game also has an interesting continue feature which allows you to continue from the dungeon where you were killed, with your score reset to zero. Funny that Nintendo would be the one to first include such a feature (also in Goldcliff ), since today they are notorious for the lack of continue/ingame save funtions in their mario/zelda games, punishing little mistakes by having to complete a whole level again seems to be the Nintendo policy these days...