An acquaintance bought this game for this reviewer as a birthday gift. Shadow of the Ninja, or KAGE, as this reviewer prefers to call it (as the imported Japanese version was the one that was purchased), was certainly not a game that this reviewer would expect to be enjoyable at first (having been disappointed by so many poorly made NES games earlier after all).
The first level starts with dour, dark colors and textures, complete with rain in the background to project an oppressive atmosphere. Being the impressionable kid, this reviewer was not exactly enamored by this. However, in hindsight, such an introductory level was certainly a rarity for the NES at the time and was proof of its developers' talent at building a game around its theme.
The story is as expected when the romanticization of otherwise ominous individuals are involved: a pair of ninja are out to right the wrongs committed by a tyrant (with otherworldly powers, as is usually the case). It's a very simple story, and thankfully so, as it keeps the player focused on what should be done.
Being agents who solve problems with covert aggression, the taciturn pair have access to a few sets of weapons that can be retrieved from caches placed throughout the five stages of the game. The two primary weapons, limited as they are, are upgradeable and both serve their purposes and function well: the katana is a virtually catch-all weapon and would be favored by veterans of the game, but the kusarigama has directional attacks that would be very handy when exposing oneself to enemy fire is not desirable. Retrieving the same weapon power-up upgrades the weapon; this will be an often-performed act, as incurring too much damage (close to 15% of the player character's health bar) will cause degradation of the weapon.
However, it has to be noted that the other primary weapon power-up, once picked up, replaces the existing one, resetting them right back to the puny first level of upgrade. This is a rather regrettable design oversight, but most power-up caches can be hit from far away and their contents are pretty much fixed, so with a little bit of memorization, the unwanted ones can be pretty much avoided. They disappear after a while, as well.
The other two secondary weapons are shurikens and bombs, the latter being a little too situational to be useful (but they do certainly do tremendous damage). The shurikens appear to have a mind of their own, often homing in onto enemies on-screen. They are not very powerful however, but a smart player will realize that they are very effective against small irritating enemies that would be too difficult to hit with primary weapons. These weapons cannot be upgraded and are limited in supply, but they can be replenished (though it is not immediately clear which of the two a player character has; the same counter is used for both weapons).
The enemies in the game are surprisingly varied, especially from stage to stage. There are few repeated models, and even if there are any, they appear to return with new forms of attacks while retaining the same deceptive appearance. (For example, there is a certain cyborg soldier dude with a big gun who acts much like a turret, but whose later versions have more firing modes and stances that make his removal more difficult.)
New enemies are often introduced in a sudden, memorable manner, such as shoulder-ramming dudes who zip across the screen with clear acceleration and deceleration (quite a rarity in NES games in those days). Sometimes, it is not immediately clear what they do, such as a drone that hugs the ground but zooms around on rocket thrusters once it detects the ninja stepping on the same platform it is on.
NES games of those days were often plagued by cheap enemies who can take a beating without a single blink, making most games much harder than they should. However, in this game, many regular enemies - especially the faster ones - can be stunned indefinitely, making them easier to handle. Certain projectiles thrown by enemies can also be stopped mid-air as well. Also, unlike many games of the time, enemies tend to have extra attack animations designed into them, especially the ones that behave more like turrets. (These animations do not appear too cheesy either, e.g. in a "I-am-SO-going-to-HIT-you" way.)
All these nuances serve to provide much helpful warnings for purposes of evasion, reward players who learn how to counter enemies and help them recognize patterns more easily. They go a long way to mitigate the culture of cheap deaths that often permeated NES games of the time.
(Also, the common-place pits and holes which player characters can accidentally fall to their doom are much more forgiving here. Player characters in this game only incur a reduction to their health when they suffer such a mishap, later appearing lying down on the platform from which they made the clumsy jump before getting back into the fight again. It is odd, but it would give the impression that the ninja had come prepared for such occurrences - as they should be.)
This game also has interesting boss fights, especially the last couple where their attacks subtly change as they take more damage. A select few are, unfortunately, major push-overs once their patterns have been identified. However, most bosses have randomized patterns, which in turn is balanced a bit by the fact that they can be stunned briefly to tuck in some damage before they return out-of-reach.
However, it has to be noted that many bosses appear to have health bars that aren't displayed properly. Their health bars only appear to degrade once they have taken sufficient damage. On the other hand, many of them have visual cues independent of their health bars, e.g. as they weaken, a change in texture, colour and, as mentioned earlier, attack patterns occurs.
The graphics are pretty good, even for an NES game. However, they are perhaps a little too complicated for the NES to handle, as blinking of the player characters occur very often whenever they obtain power-ups or get injured - the latter resulting in an injury animation that should have been displayed clearer.
The animations were quite detailed and numerous for a game of its time. The player characters are in particular a joy to watch in platforming sequences, where a competent player can guide them fluidly past obstacles and enemies. Yet, it has to be told that the game appears to make too much use of turret-like enemies: guards who stand on the spot firing guns, ninja/shinobi who crouch in a spot indefinitely shooing away the players with flurries of jabs, and, of course, actual turrets. Fortunately, many of these enemies still appear and behave in sufficiently distinct manners.
The level design in this game is quite competent, though a few levels resort to obscuring otherwise easy-to-defeat enemies with props that should have been in the background. However, the slightly struggling graphics also appear to mar the level design. Certain levels have gradually transitioning screens, e.g. the typical rising pool of lava scenario, that are not enacted well, resulting in screen panels getting scrambled at the edges of the screen.
The music is upbeat, as can be expected from a game with themes that are similar to Ninja Gaiden's. Track-stopping and -fading scripts are used to good effect in this game to lend brevity to situations such as the eventual defeat of bosses or transition to the next sub-stage.
Perhaps the greatest strength of this game is that it is a title with effective co-op play. There had been other NES titles with co-op play, but many of them, dubiously enough, did not have friendly fire or similar issues where one player could obstruct his/her partner designed out of them. Not so in this game, where the player characters have very unique models which just cannot overlap such that they are obscured. They also move past each other without clipping/collision problems (as it should be when a pair of ninja fight side-by-side), and the screen only moves forward if both makes relative progress.
In conclusion, Yami no Shigotonin KAGE was one of the better NES titles of its days, sufficiently addressing many of the frustrating issues plaguing 8-bit games of its time.
(P.S. It is important to note that the GameBoy adaptation of this game, which this reviewer also played, had been redesigned into a spin-off the Ninja Gaiden series, and thus have nearly exactly the same plot and villains, at least in name. Also, the Wii Virtual Console service is offering this game.)