It's fair to say that the Metal Slug series is one of the more hardcore doing the rounds on the video game circuit. With the first six games in this side-scrolling shooter series debuting on NEO-GEO hardware before later being ported to home consoles including the PlayStation 2, it's no surprise that the majority of gamers aren't aware that such a cult following exists for it. In its 10th Anniversary year the series received title number seven in the shape of Metal Slug 6 and the lovely people at SNK Playmore made the wise decision to bring the entire collection to a new generation of gamers. Metal Slug Anthology was born.

This collection of seven titles will be released on the Wii next month, but for now I'll be looking at the PSP game. Right from the off you have access to the seven games and the main menu also lets you change some global options. From here you can set the game to use limited or unlimited continues, customise controls and choose which display format to use. By default the games will be shown in 4:3, but the options are there to run in the original pixel format or stretched to fill the PSP's screen. Stretched makes the games look rather ugly, making the other two options preferable despite the black borders around the game window.

Played through in succession, the seven games give newcomers a superb run-down of the classic series, although anyone unfamiliar with old-school gameplay mechanics might find the going a little tough. For the most part, your character can take a single shot and that's it - life bars, health upgrades, replenishing health and mid-level saves were obviously developed to please a generation of gamers unwilling to put up with instant deaths and replaying whole games. It's safe to say that for many gamers, Metal Slug Anthology will come as quite a shock to the system.

It's perfectly possible to run through each game using unlimited continues, something that might be worth doing to get a feel for the gameplay without suffering the insane difficulty, but this of course wouldn't be getting the most from the games. The series has been designed to be tough and to make even the hardest of men break into a sweat. There's every chance that you'll never manage to finish each game without resorting to unlimited continues - it's that hard - but simply trying to beat your high score is reward in itself. A second player can help out via wireless, but sadly two copies of the game are needed.

So, while this collection is great for newcomers, what's in it for veterans? It's true that six of these games have been released on home consoles in the past, but Metal Slug 6 has only been available on the Atomiswave arcade board. This collection marks the first time the seventh game in the series has been playable on a home system and this is big news for die-hard fans. Considering single Metal Slug games have been sold as standalone titles in the past, the fact that Metal Slug 6 has been made available alongside the entire catalogue of titles is incredible.

The series remained pretty much the same for years, with shooting, grenade throwing, POW rescuing and Slug riding (vehicles of some kind) evident in each new release. Metal Slug 2 onwards offered a selection of characters, but this did little other than place a different looking character on screen. Metal Slug 6 made some fairly big changes, introducing six characters that actually feature different attributes and the option to play on an easier difficulty. Choosing this option gives your character unlimited use of the machine gun (instead of the pistol) and removes the final mission. The look of 6 is also drastically different, with the sharp appearance of the previous six titles gone in favour of a softer style and a more dynamic camera.

Bosses are often extremely large and very tough

Visually it's incredible to think that Metal Slug is over ten years old, as even today it looks sharp. Each game has a real character to it that you just don't see in many modern action titles and you'll be constantly surprised by the little details in each mission. Bosses often look spectacular too, even if they come at a cost to the frame rate. The arcade titles featured periods of sluggishness and the same is true of the PSP ports, but at times you'll be thankful for the slightly slower pace. The one major letdown in this PSP game is loading. Load times are a little longer than I'd have liked and there are often pauses during the action that can be quite jarring - still, it's a small compromise for having the entire series in the palm of your hand.

Adding even more value to the package are numerous unlockables that can be bought using tokens earned by playing through each of the games. Music from the series can be unlocked and transferred to your memory stick and wallpapers can be used to add decoration to your PSP's menu screen. Additional art work and an interview with the game's development team can also be obtained, rounding off a nice bunch of additional content. What's more, each game can be saved on the spot should you run out of time while playing, which might be an option that's looked down upon by perfectionists but will come as a relief to the less hardcore players.

And that's your lot. There's no doubt that Metal Slug Anthology offers incredible value for money and the whole series together on one disc makes it essential for Metal Slug fans. Whether or not newcomers will take to what is often a demoralising experience will depend entirely on the individual. If the idea of single shot kills causes a sharp pain to run down your spine, stick to modern action offerings, but if you want a challenge look no further.