The Contra franchise had been a steady revenue-earner for Konami for years after its debut as Contra. Contra III: The Alien Wars was yet another entry to the franchise. This time, the enemy had been clearly defined as alien in nature (whereas in previous games, the enemy had been confusingly described as terrorists, aliens or both).
Moreover, this is the first Contra title that Konami had boldly ported over from the platform that it had originally launched on (the SNES) to the GameBoy without a significant name change. Unfortunately, as the SNES was a more powerful machine than the GameBoy, Konami had to remove many features from the game, such as a multitude of bosses, the Laser gun (the beam of which apparently could not be rendered reliably on the GameBoy) and reduction of the sizes AND number of stages to accommodate the relatively lower data capacity of the GameBoy cartridge.
Most importantly, the game design that was very refreshing in the SNES version is missing in this game, which is the ability of the player character to carry two weapons at a time.
Consequently, the harsher of Contra's fans can deride this game as a half-hearted port that attempts to cash in on the fun of the SNES version (which was an explosive entry on a 16-bit system). However, if a player can consider this game solely from the view of a GameBoy consumer, it is still quite satisfying.
Comparisons with the earlier SNES version aside, this game packs the same trademark fun of the Contra franchise: a determined commando had been unleashed on a hostile force that is bent on global destruction and/or domination, and it is up to the player to direct the wrath of this hero while gunning down hordes of inhuman but otherwise stupid goons and bosses.
There had been a few fundamental changes to the design of this Contra entry since the first few games. The first and most apparent one is that the player character's standard weapon is now the Machine gun; the player no longer needs to mash the fire button furiously to fire volleys of shots.
Another is that the player character is now able to climb walls and jump off them, which is a new ability that the game does very well in showing off in scenarios that require a lot of climbing and jumping. (However, these sequences do seem fewer in the GameBoy version.)
The Fireball gun from the previous games has been re-designed as a true flamethrower. While it is very short-ranged, it is, like its predecessor, capable of dealing a lot of damage in a short time. It is also the only weapon capable of reaching enemies behind physical barriers; this is likely a design oversight, but one that is quite welcome as it made the Flame-thrower much more competitive. In fact, for many boss fights, it is required if the player wishes to perform speed runs.
The smartbomb power-up in the previous games can now be hoarded, thus providing a way to compensate for the substantially more numerous enemies that had been gradually becoming a norm in Contra games.
While there are reduced number of stages in the GameBoy version, the ones that remained are still pretty fun to play through, even if they do appear to have shorter lengths. That is because the core themes of any stage, such as one with falling platforms or rails that had to be climbed along while occasionally performing maneuvers to dodge enemies and gunfire, are still there.
Stages are generally split into two types: side- or vertical-scrollers where the player basically needs to get from point A to point B (with the objective of racking up points by shooting enemies being practically optional), and top-down stages where the player has to hunt down certain objectives (the direction for which is handily indicated on-screen by arrows).
Stages end with flashes of the same couple of concept artworks for the hero of the game, which while quite repetitive, at least gave the player (and the Contra fan) a very good idea of how the player character looks like for the first time in the series (whereas in earlier games, he was easily mistaken as a copy of Arnold Schwarzenegger by quite many).
As in the first game, power-ups appear on-screen, locked away in floating containers that are taunting the player and practically begging to be shot down. As has been a signature design of the series, blowing them open yields simple letters with wings that represent one power-up or another. The console versions would appear to have greater contrast for these power-ups, but their flashing visual effects are adequate enough for the GameBoy version.
(It has to be noted here that from the appearance of the containers, they would appear to belong to the enemy, who apparently ferries around supplies in flying containers that can be easily shot down and pilfered by those who oppose them.)
Enemies, as mentioned earlier, are mostly idiotic goons who run pell-mell towards the player character, occasionally firing shots at him. The rest are turrets who lob bombs or fire more shots at the player character. However, there are new enemy designs that require the player to use a slightly different approach to them, such as armored caterpillars who slink towards the player in a less-than-predictable manner.
Interestingly enough, coming into physical contact with certain enemies will not result in instant death in this game. Certain enemies can be jumped onto so as to have their heads walked all over (while being riddled with gunfire) or hung onto, while the player character uses them as leverage to fire on other targets before turning his gun on his ride.
(Super Contra had a few enemies which the player character can touch, but these were so, so few.)
On the other hand, some enemies also appear to be invulnerable to gunfire for the duration of certain scenarios, such as one where the player character is threatened by a bipedal robot/monster who is trying to stomp him while bombarding him with missiles launched from short ranges. This scenario was suspenseful the first time around, but a wiser player will notice that the game does not give any indication that said enemy is invulnerable and the player has to endure the scenario, which is very, very different from the usual gleeful run-and-gunning.
The bosses in this game are the usual over-sized war machines or monsters that can be expected from Contra titles. Like their predecessors, they have easily memorizable attack patterns that can be exploited for speed-runs. However, to the credit of their designers, they do require a lot of quick reflexes and/or practice before they can be defeated in a way that would have been humiliating to them.
The GameBoy, for the most part, could run the game quite well, though there were many moments where sprites were not rendered properly and lost parts of themselves here and there, especially when there is a lot of action on-screen. Fortunately, this graphical setback is not so big as to hinder gameplay too much.
The audio design is surprisingly more solid than the graphics. Like in the previous games, everything happening on-screen has a unique sound-clip to indicate that they have occurred. The GameBoy does a pretty good job in making sure just about every sound-clip is emanating from the speakers.
Co-op mode is starkly missing in the GameBoy version, but to somewhat compensate for the missing feature, a password feature that lets the (lonely) player continue where he/she left off has been introduced. It does not appear to preserve scores, however, making this feature at best only useful if a player is looking to practice for the performance of speed-runs.
In conclusion, Contra: Alien Wars for the GameBoy may be a terrifically stripped-down version of the SNES version, but these are largely due to the understandable limitations of the GameBoy. As a GameBoy game, however, it is still worth spending time on.