Ah, the vertically scrolling shooter. It hasn't really been a videogame genre I've been overly enthusiastic for since my Spectrum days, but when I heard about Nanostray, it piqued my interest. Perhaps it was that 'Old Skool' appeal, or maybe I've just gotten tired of playing derivative FPS titles... After a few minutes' play, it becomes very obvious that despite the upwardly-spiralling power of gaming hardware in the last twenty years, the scrolling shooter has remained a genre that's been relatively untouched by the technical revolution. The more things change, the more they stay the same; a trite way to sum up the scrolling shooter genre, but an accurate one. Other than looking a heck of a lot prettier than genre progenitor Xevious, the fundamentals of Nanostray are essentially the same: learn enemy wave patterns and blow up stuff for a High Score.

No detailed breakdown of controls is necessary here - suffice to say, if you've played any shooter from the last five years you've probably seen it all before: standard weapons, secondary power weapons, smart bomb, etc. However, without having any peers in the genre on the DS, Nanostray is certainly worth investigating if you want to satisfy your twitch-gaming urges.

The game has four modes of play: Adventure mode, with which you unlock stages for the other two Single-player modes; Arcade mode; Challenge mode; plus the Multiplayer game. I'll start with the Multiplayer and get it out of the way first, as you probably will too, because frankly, it's rather rubbish. The Multiplayer mode has four dedicated stages for head-to-head play, but I didn't find them nearly as challenging or interesting as the Single-player levels. Multiplayer games have two end conditions that you can select - Timeout or Sudden Death. Sudden Death does exactly what it says on the tin: you have one life, and if you lose it, you forfeit the game. Timeout, however, will let the game run until the victory condition of one of the four Multiplayer game types has been achieved.

It really is a quite stunning DS title

It's all fairly self-explanatory; the 60-second and 120-second modes are quick smash-and-grab rushes for points; the 25k mode is likewise a race to see who reaches a score of 25,000 the quickest; and the final game type is the most interesting - Bonus Race. This game type is a timed run, where the two players try to grab as many bonus power-ups dropped by destroying enemy waves as they can. The hook is that not all of the power-ups are beneficial. Whilst some speed you up and others contribute to your score, others prevent you from firing or drastically cut your movement rate, which is invariably fatal if you're playing in Sudden Death mode. Perhaps "rubbish" is a bit harsh, but given the quality of the Single-player game, the Multiplayer doesn't really cut the mustard. Given the wireless capabilities of the DS, a co-op mode for the Adventure levels really should have been included and must be considered to be an opportunity missed.

The Single-player mode, therefore, is where it's really at, and the natural starting point for Nanostray players is by necessity the Adventure mode. The eight Single-player levels are broken up by difficulty: three levels of 'Low Resistance', another three of 'Medium Resistance' and two of 'High Resistance'. You need to conquer all of the levels in the 'Low' bracket before being able to progress to 'Medium'. After mastering the medium difficulty levels, the two 'High Resistance' levels are given to you one at a time. The Adventure mode has three difficulty levels, Normal, Advanced and Expert. Normal allows you unlimited game continues (a bit like "Insert Credit" on an arcade cabinet), lets you have five ships per credit and gives you three smart bombs per life. Advanced and Expert cut down on the number of ships you have per credit (4 for Advanced and 3 for Expert), reduce the number of smart bombs you get after being killed and both modes only allow you to continue three times. The learning curve is well judged; though expect to play a level a dozen or more times before you pick up its nuances, especially if your twitch-gaming neural pathways are a bit flabby. The stage design is good, and whilst the movement is essentially restricted to a 2D plane, there is a real sense of height and depth. Some enemies can even be flown under without jeopardising your ship, though it takes some experimentation to find out which ones.

Nanostray, it must be said, is one of the most graphically impressive titles on the DS and a very handsome shooter. The texture quality is excellent given the relatively puny processing power of the DS and the vibrant stage backgrounds add lots of atmosphere to the game; the viciously erupting gouts of lava spewing from Hibashira Plains and the ultra-hostile urban sprawl of Chuuroh City rank amongst my favourites. All in-game objects are rendered fully in 3D, and it's a pleasant surprise to find that the frame rate rarely suffers from all the polygons being pushed. There are a few dips in animation speed when you have lots of enemies and pyrotechnics being drawn simultaneously on-screen, but nothing which hampers game play too much.

The eight weapon effects are pleasing on the eye (especially the power weapon effects), and each weapon occupies a useful niche, whether it be in wave destruction or in Boss battles. Enemy variety and design is good, and there's always something nice to look at on the screen (mainly to distract the unfocussed from concentrating on the bullets, making them lose yet another life). Sonically, the game is also impressive, with satisfyingly chunky sound effects and enthusiastically pulsing techno-themes to accompany the destruction.

The pace is kept refreshingly high throughout and the level of hand-eye coordination required in the final two 'High resistance' stages climbs towards mesospheric. Boss battles are mainly tests of endurance and concentration: once you've picked up their movement and firing patterns, they're not too hard to defeat, but the learning process can be a long and painful one.

Once a level has been beaten in Adventure mode, you can then think about tackling them in Arcade or Challenge mode. It's the Arcade mode which provides most satisfaction, as you play through each level with just three ships and only regain one spent smart bomb with every new life. Shin'en have set up a world ranking website for you to upload 'Nanocodes' once you beat a particular stage, which allows you to see how your performance ranks against others around the world. This provides a huge incentive to improve your scores and nudge yourself further up the table. To get the highest scores you're required to take advantage of the bonus scoring system in the game.

You're rewarded for not using smart bombs, losing lives and the all important Valour bonus can be a significant source of points. Valour can be gained by only shooting your weapon when necessary (rather than just holding the button down) and by collecting coins by flying through them, instead of using your 'Attract' ability. Most points are gained, however, by not using your secondary power weapon until you reach the stage Boss. Destroying complete waves of enemies will drop a blue coin, worth 500 points. If, however, you destroy wave after wave of enemies without using your power weapons, the value of these points rapidly stack up: 2x500, 3x500, etc. On a stage where there may be 30-40 waves of enemies, the value of relying on your primary weapons alone rapidly becomes apparent (30x500 is a lot of points!) and you will need to do this if you ever hope to compete with the big boys in the world rankings.

The Challenge mode is similar to the Arcade mode, except it tasks you to complete levels according to certain criteria, such as having only one ship, or not having secondary power weapons. Beating a Challenge will reward you with a picture you can view in the game gallery, accessed from the main game menu, but otherwise provides the player with no incentive to play them other than to test their skill.

There are only really two flaws in the game. Firstly, the touch screen integration is poor. It's only really used to allow you to switch weapons on the fly (which unfortunately requires you to take your thumb away from the firing buttons) or to scan for the weak spots on end of level Bosses. The radar on the touch screen is also entirely superfluous. It's a nice cosmetic touch, perhaps, but an entirely unnecessary distraction during game play. Secondly, you can destroy enemies that have moved beyond the edge of the rendered playing area. This can result in you destroying enemy waves before they even come on the screen, which prevents you from being able to collect the blue coins needed to rack up your score. Whilst you might consider this a blessing when you first start to play the game, it rapidly becomes an annoyance as you improve your level of skill and strive to get ever closer to that perfect score.

Fortunately, committed players will learn how to work around this flaw in the combat modelling, and the annoyance factor never becomes a fatal one. Overall, Nanostray is a solid, good looking title that sits neatly in its own little niche in the DS portfolio. While it's nothing revolutionary and doesn't really fulfil the potential of the platform it has been designed on, until the next DS shooter comes along, it will more than satisfy the needs of the twitchiest of fingers.