Natsume's Shadow of the Ninja tends to be written off as a Ninja Gaiden clone. The comparison holds some water; after all, Tecmo swooped in and snagged the Game Boy sequel during development and had it reshaped into an actual Ninja Gaiden spin-off. It doesn't get much more direct than the publisher of the game you're accused of ripping off coming along and saying, "Hey, let's make this a legit game."
But simply calling it a Ninja Gaiden knockoff is too reductive and fails to get at the full expanse of the game's inspirations. Better to call it a clone of every great NES action game, really. Why stop at just one when there were dozens of greats to borrow from? Shadow of the Ninja plays almost like a "greatest hits" compilation of NES ideas, reminiscent in nearly every way of many more popular classics. The indie game scene is jam-packed with retro-style games that offer a pastiche of NES game ideas, but Shadow beat them all to the punch.
What it really captures from the NES era, more than anything else, though, is the way those games felt as if they had been created by people who absolutely hated their customers. Insane, sometimes unfair difficulty was a matter of course on NES, and for good reason; those chunky cartridges could only hold so much data, and NES games tended to be terribly short. If they were as lightweight and easy to breeze through as most modern platformers, those poor kids of the '80s would have been out $50 (that's about $125 in weaksauce modern money) for an hour's entertainment. So NES developers made their creations crushingly, despair-inducingly difficult.
And holy wow, did Shadow's creators go all-in. This game wastes no time setting about the task of ruining a new player; the game's five worlds are divided into several stages apiece, and by the time you reach world 1-2 you're already dealing with absolutely hair-pulling challenges. The difficulty balance in Shadow really feels nothing like Ninja Gaiden, which featured a huge variety of masterfully placed enemies in enormous numbers. Here, you deal with fewer foes, and they don't instantly respawn the moment you backtrack. But they're extremely dogged, and unlike Ninja Gaiden's bestiary of foes they don't go down in a single hit; it's more of a Castlevania approach, where most enemies can soak up multiple hits before fading away in a little 8-bit implosion.
The first of the game's worst opponents comes in the form of strange rushing foes, reminiscent of Super Mario World's Chargin' Chucks. While they don't damage the player's ninja directly, they move with incredible speed and will shove you quickly along the ground until you hit an obstacle or, more likely, fall into a pit. They absorb a ridiculous amount of damage and will continue to chase you through the stage until destroyed, and they're placed strategically in the worst possible places, guaranteed to knock you into pits full of monsters or, worse, into pits with no bottoms.
That's not a light threat in this game: Shadow grants your ninja warrior a significant life bar, but no extra lives. Once you die, that's it. You're allowed a measly five continues, and your health doesn't regenerate automatically between stages. Shadow of the Ninja becomes a war of attrition (mitigated only somewhat by the occasional appearance of health pick-ups along the way), and if you choose to take on the two-player mode, both ninja share that pool of five continues between them.
With that meager stock of continues, you're forced to battle through more than a dozen stages packed with durable foes who zip quickly across the screen, fire projectiles before you've even scrolled them completely into view, and fill the playing field with sprays of bullets and spears. Tough foes stand unmovable in narrow passageways, so even if you give in to pragmatism and decide to forego killing each individual enemy you're still going to have your face rocked by burly dudes with bazookas, whether you like it or not.
It doesn't help that Shadow's weapon system is incredibly limited, forcing players to make hard choices. You can only carry a single weapon at a time; if you collect a throwing weapon, you're stuck using that weapon until the limited stock runs out. The two main weapons, a katana and a bladed chain called a kusarigama, present a tradeoff: The former is fast but extremely limited in range, while the other is slow and only good at a distance, doing no damage at close range. You have to collect these weapons to swap them, so you need to know which tool you'll need for each segment of the game.
But that's Shadow of the Ninja in a nutshell. It's not a game of response and reaction but rather one of memorization and commitment. You even need to commit to weapon selections; if you collect multiple upgrades of the same tool, that ability will power up... at least until you take too much damage, at which point it will be downgraded for you. Everything in this game is stacked against you; even if you manage to defeat the brutal final boss, Shadow still has one nasty last little parting shot for you. This is not a game that goes down without a fight.
But in return for your agony, Shadow of the Ninja offers you a lively romp through little snippets of every NES game you loved (well, except maybe Tetris). The music and ninja protagonists appear to have been ripped from Ninja Gaiden, yes. But the weapons and enemy patterns bear a strange similarity to Taito's Power Blade. The backgrounds and sprites look like some lost Sunsoft game. And then there's that two-player simultaneous mode, a la Contra.
On top of that, Shadow has plenty of its own little grace notes. Players could choose to control one of two ninja from the outset, one male and one female, both of whom wielded the exact same powers and skills. Rather than copy Ninja Gaiden's wall-cling ability, the hero or heroine could instead hang from walls and mount platforms. It played like a load of other NES games, but not exactly like them.
Definitely near the upper tier of NES games, although it rather lacks its own visual style.
Great, rockin' chiptunes, though they can grow repetitive.
The control scheme feels a little clunky, especially when mounting platforms. The single-weapon mechanic can be especially frustrating.
Provided you don't blitz through the game in half and hour with save states, Shadow of the Ninja requires skill, practice, and patience.
Short on originality and tall on challenge, Shadow of the Ninja represents a solid B-class NES action game — an entertaining if somewhat maddening way to spend a weekend (or however long it takes you to master the game). If you've mastered the classics, Shadow's a decent semi-classic to waste some time with.