Another incarnation of Perfect Dark also appeared on the Game Boy Color, although the style of the gameplay was altogether different. For the GBC, Rare favoured a much more stealth-based approach. PDGB forms a prequel to its Nintendo 64 brother, as you guide Joanna Dark through her training and then out to her earliest missions. Owners of both games can use the GB Pak to unlock some of the best cheats in the N64 version: at first, I thought this was a gimmick to guarantee sales of the weaker Game Boy game, but fortunately that more than holds its own.
Graphically, Perfect Dark puts the majority of GBC games to shame, demonstrating what can be achieved with a little ambition from the developers. There are occasional glitches, with bits of scenery being rendered in the wrong order, but for the most part it is mighty purdy. Many of the set pieces have static, pre-rendered backgrounds, and those in particular give the now-aged GBC a chance to show off its graphical skills. The quality of animation on Joanna and the guards is top notch, being both smooth and convincing. All the graphical elements adopt a realistic style which is frequently difficult to capture with such low resolution, but the artists behind Perfect Dark succeed admirrably.
Audio too is top notch, especially considering the poor reproduction quality permitted by the Game Boy. Gun shots and the grunts of dying guards are reasonably authentic, and PDGB is perhaps unique among Game Boy games in featuring sampled speech. The quality is inevitably quite low, but coupled with the text script, it is certainly intelligible. How much this actually adds to the game is debateable; personally, I found it to be a case of "because we can" on Rare's part.
However, the gameplay itself is where Perfect Dark can really excel. The top-down perspective is perfect for the stealth-driven missions, where avoiding detection via crafty headshots and appropriate use of cover is your only chance for survival. In this sense, the game feels much more like a simplified Metal Gear Solid than it's action-packed N64 counterpart. Some of the cover available does feel a little contrived, for example the guards are unable to spot you on the other side of a desk or a bed, but at least it keeps the mechanics of the game pure.
The multiplayer element, in my brief experience of it, was not as compelling as the main game. In the interests of stealth, the default speed is a silent walk, while running requires a tricky double tap. This clearly counts against fluidity of motion in multiplayer, where sneaking up on the single opponent is of little value. The variety of multiplayer modes, not all of which I have yet unlocked, was, however, appealing, and multiplayer may hold some lasting value for evenly matched opponents.
Finally, the issue of the length of the game. Quite simply, I have been astounded. There is an epic series of solo player missions, built on a perfectly judged difficulty curve: the missions get progressively harder and longer in just the right proportions to keep you challenged but never frustrated. On top of that, there are a number of bonus challenges that you can, and will, revisit later, both boss matches and arcade-style challenges. In short, it's both huge and addictive.
To conclude, Perfect Dark is quite simply one of the finest games on the Game Boy. That a game for such a format can be so aesthetically pleasing and yet so vast, so carefully balanced and yet so eminenently playable, is nothing short of a miracle, and is as indisputable a testament to the talents of Rare as can be found. My advice to anyone with suitable hardware is Buy This Game Now. Just do it. It's superb.