Ninja Gaiden 1 and 2 are commonly agreed to be classics of the action platforming genre and of the NES more generally. They both combined tight controls, solid presentation, good music, fun level design, and high difficulty levels for good times.
However, there is a bit of a tendency for NG2 to be seen as an improvement over its predecessor. The common line is that NG2 added a bit more interesting level design and climbing controls, while also toning down some of the frustrating elements that made NG1 so difficult.
I disagree. While I love NG2 (which was actually my introduction to the series), I think that NG1 had a coherent, tight game design, which encompassed the controls, the level design, the music, and the presentation. NG2 is a fun game, but the added and modified mechanics, IMO, took away from the coherence. It made NG more like other games, rather than focusing on what NG1 did best: make you feel like a God Damn Ninja.
I'll sum this argument up in two parts: 1. Ninja Gaiden's design, 2. Ninja Gaiden 2's changes
Ninja Gaiden 1: What is an action platformer?
I think the big source of confusion for NG1 is the lack of awareness of genre. To put it simply, I don't think NG1 is really a platformer at all. Most of the game is about combat management. How do you approach an enemy? How do you respond? What items do you use?
The environment (including platforms) plays a role, but the game isn't about making hard jumps. It's about dealing with enemies -while- making hard jumps. It's about knowing that God Damn owl is coming and being able to deal with it, while jumping a chasm and latching onto a wall. In general, this isn't a platformer. This is an action game that uses platforming elements to accentuate the action.
Once you realize that the focus in NG1 is on making the player feel like a GD ninja, and that it's actually an action game, everything else makes sense. I'll be discussing particulars in this order: 1. Pop-up enemies, 2. Tunnel levels, 3. Controls, 4. Music/Presentation
1. Pop-up enemies
One of the favorite criticisms of Ninja Gaiden 1 is that the damn enemies pop up out of nowhere. There are lots of points in the game where, if you just stand still, an endless barrage of clones will continue to pop-up and attack you in the exact same way. This, to many, feels cheap and unfair. And, to some extent, they're correct. However, there are two damn good reasons for this mechanic:
a. KEEP RUNNING!
Because of the pop up enemies, there is a strong incentive in NG1 on RUNNING AS FAST AS YOU CAN THROUGH EVERY GOD DAMN AREA. You want to stop and take a break? TOO BAD, THERE IS AN ENDLESS BARRAGE OF NINJA COMING! You need to slow down and get a tactical-YOU'RE DEAD. YOU'RE ALREADY DEAD.
The pop-up enemies -force- the player into a certain kind of playstyle: fast, visceral, responsive rather than generative. In other words, it forces you to play like a GD Ninja.
Sure, there are other ways of forcing this kind of play-style: timer, slowly reducing health, etc. However, I'm not sure that any of these approaches is an appropriate replacement. Not only do they have their own problems, but they don't force the same -kind- of speed onto the player as pop-up enemies. In NG1, your speed isn't forced onto you by an abstract timer. It's forced onto you by ENEMIES POPPING UP EVERY WHICH WAY. Complaining about pop-up enemies in NG1 feels sort of like complaining about "all these damn bullets" in a bullet-hell game. It just shows a lack of awareness of what makes a game a game.
b. Tunnel levels
NG1 doesn't have very interesting level design from a platformer perspective. Almost every level is a one screen tall tunnel, going either left-to-right or right-to-left. However, again, NG1 isn't a platforming game. It's an action game where you're a GD NINJA, and the tunnel levels are perfect -for this game design.-
I think my argument will be more clear once I discuss NG2, but, suffice to say, the meat of each level is RUNNING AS FAST AS YOU CAN through a NEVER ENDING GAUNTLET OF ENEMIES. The level design is there to emphasize this playstyle. There are platforming flourishes, as well as walls to climb and other features here and there. However, the level design here is closer to Ninja Warrior on Spike TV than Super Mario Brothers or Mega Man. Speed and combat. That's the whole game.
3. Overall, the controls in NG1 (as well as NG2) are tight. I mean, like, really tight. Like jump a bit in the air.. but manage to attack twice in the air tight. Tighter than damn near any other NES game tight. This is a game where you're given all the tools to be a total badass. You just need to find a way to use them. Again, this is all meant to emphasize the fast-paced combat mechanics and the run, run, run playstyle.
However, one element of the controls that gets criticized is the wall controls. Rather than simply climb up and down walls, you need to jump up them with some somewhat difficult timing. I'll get back to this when discussing NG2, but there are two things I'd like to say about wall-climbing as its constituted in NG1: a. It was designed consciously to be like this. Remember, there -are- surfaces in NG1 which you can climb NG2-style. They already exist in NG1. They just -chose- consciously to make most walls more difficult to climb. b. The added complexity of the wall jump, in my mind, makes it all the more satisfying to utilize. Really, it's not as hard as some make it out to be, and it's a lot more fun to successfully pull of than simply pushing up and down.
I don't have a lot to say here that hasn't already been said. The presentation is awesome. The music is awesome. Go listen to this: http://www.youtube.com/watch?v=OZLXcCe7GgA
Doesn't that make you feel like a ninja? Doesn't that make you just want to go out and do epic things with anime-esque abstract movement effects rolling in the background?
Again. This game is all about being a GD ninja. Presentation and music just add to the effect.
WHAT DOES NINJA GAIDEN 2 DO DIFFERENTLY
1. Level design
The tunnels in Ninja Gaiden 1 are perfect for speedy, actiony, intense gameplay. NG2, however, went far more into platforming. Platforms, in general, play a much bigger role in NG2; there are vertical areas rather higher than one screen; levels, in general, have a much more expansive feel to them; and, most importantly, there are the environmental hazards.
In my view, while these are find additions to a platformer, they miss the point of NG1 entirely. Let me give you an example: how do you play the second level? With the wind gusts? Oh, what's that? You just stand there until the wind is right. Hrmm. Okay, how about the level where the lights go out. How does that impact your play style? Oh, you just stand and wait until you can see fine? Hrmm. How about the level with the lava, where the rocks spit out intermittently? How do you deal with the rocks? Oh.. more standing and waiting. Hrmm....
Standing and waiting is NOT what NG is about. It misses the whole point. It's like playing a Sonic game without loop-to-loops. And you do it in NG2. A lot.
The other hazards don't seem to get the point either. The water hazard makes you go more slowly half the time, and the ice level takes away the tight-ass controls that the series is known for. I could forgive the game if there was a strong focus on dealing with enemies while managing the hazard but, truth be told, that's not entirely true. Sure, enemies attack you, but it's nothing like NG1. The platforming elements in NG1 were infamous for piling on the deaths. Half the time in NG2, while you're dealing with a hazard, you're, at most, dealing with one or two slow-or-even-standing-still enemies. It's just not the same at all.
The multi-tiered platforming also misses the point. When you mess up in NG1, you die. When you mess up in NG2, you.. redo all the pain-in-the-ass jumping you just did. It just doesn't feel as visceral or intense. It feels more like Mario shoe-horned into NG1 than like a proper ninja adventure itself.
Let me make this short: nearly everything about NG2's combat changes makes things easier for you. Special powers are less expensive, and you earn more power. You can attack off walls. You can have up to two clones. Etc. etc.
However, the overall impact of these changes is to: 1. Make the game easier, 2. Make combat less precise. In NG1, other than a spattering of shurikens, you had to rely on the tight controls and your own instincts. In NG2, you don't even need to do anything half the time. When clones are combined with plentiful special power, combat almost ceases to be a frightening event at all. It just takes the feeling of being a ninja away. With the fire power you pack in NG2, combat is almost more like Contra with a health bar than NG1. Almost.
3. Wall climbing
Again, there is a loss of ninja badassery and an expansion of accessibility and platforming. Walls are much, much easier to climb, and you can attack off of them now. This leads to some more interesting uses of walls as platforms. Sadly, there's no replacement for successfully jumping off a wall, killing an owl with your sword, and managing to latch back on before another enemies knocks you sideways. The emphasis is just.. different.
Let me clarify the above by saying that I still love NG2. It's a great action platformer and is a solid sequel to NG1. It's also not as different as I may indicate above, as I'm focusing on the differences in order to make a point about what NG1 is. For most people, NG2 would almost seem -too- much like its predecessor.
However, I do think there are misconceptions about NG1 and 2, and I wanted to outline my viewpoint here. Personally, once you get good, there really isn't another game like NG1 on the NES. The pacing, the intensity, the skill required, and the payoff (both in terms of presentation, music, and out-and-out gratification).. it's just.. beautiful.
So there. NG1. FANTASTIC GOD DAMN GAME!