Resident Evil: The Mercenaries 3D should have been a cause for jubilation. Finally we have a game that shows what the 3DS can do, proving that Nintendo's newest handheld can handle graphics of Resident Evil 4 calibre, if not quite Resident Evil 5. Sure, there are frame-rate issues when large numbers of zombies fill the screen, or when the giant mutant bat from RE5 appears, but overall this is an impressive achievement. Locations from RE4 and RE5 have been replicated with surprising fidelity, and the various “ganados” and “majini” - from the chainsaw-wielding hardnuts to the creepy monks and the scary guys with claws - look pretty much as you might remember. The Mercenaries 3D looks good 

It's also one of the few 3DS games where the 3D really adds something to the experience. The Mercenaries is all about maintaining crowd control, and the 3D effect adds to that all-important sense of panic as the hordes threaten to overwhelm you while you hear the sound of the chainsaw starting in the distance. So many 3DS games have seemed to present 3D as a series of flat planes receding into the screen, but The Mercenaries does it right. As a third-person shooter, you'll find your hero in the foreground without seeming stapled to the surface of the screen, and you can get a pretty good idea of how far away the zombie menaces might be at any time.

If you haven't played RE4 and RE5 you might find the controls take a little getting used to. The analogue stick handles movement until you press the right-hand shoulder button, at which point the game goes into an aim mode so that you can pick off the zombies with headshots or, with a sniper rifle, take a zoomed-in view. Unlike RE4 there is a feature to shuffle around while aiming - you're not actually rooted to the spot - but in practice you probably won't use it. Playing The Mercenaries is all about moving and blasting with a careful rhythm. Stay too long in one spot, and it's curtains for you.

In short, there's nothing technically wrong with The Mercenaries. Why, then, are we feeling so stingy with the score? Well, the clue is in the title. The Mercenaries is not a Resident Evil game in the sense that most of us will recognise. Instead, it's an expansion of the bonus game thrown in with RE4 and RE5, where characters from the series engage in short, high-score shooting missions, wiping out as many monsters out as possible in a given time period.

Up to a point, this doesn't matter. Shooting zombies - whatever you call them - is fun, and the gameplay isn't as simple as it looks. Firstly, the time limit can be extended, most obviously by bashing down mysterious orange pillars, but also by tackling the zombies hand-to-hand. Shoot one and he or she will falter for a second, or even collapse. Get close and press the Y button, and your current hero (or antihero) will go into a preset move, either battering or slaying the bloodthirsty shambled. This also helps conserve ammo, which will get in shorter and shorter supply as each stage goes on. What's more, you need to string together kills to build your bonus, which is key to getting the highest scores and the best grades when time runs out.

Finally, the longer you extend your time, the higher your score will climb, but the more deadly the monsters that appear will become. As dying means an immediate “nil” points, there's a certain level of strategy in racking up the points early on, then either avoiding or conquering the heavies when they eventually turn up.

The problem is that that is pretty much the game right there. You get five tiers of missions, the first three of which are effectively tutorials, and only eight environments in which to battle. There are some variations, such as when the game throws in waves of zombies to survive, but these don't massively affect the basic play. The different playable characters offer different challenges - some are clearly weaker than others, while weapon sets change from character to character - and there are hidden characters, costumes and perks to collect as you go on.

Overall, though, it's all a bit samey and superficial. The Mercenaries is a fine game for high-score enthusiasts, but most of us will find the action gets repetitive fairly quickly. Plus, the fact that you'll need to achieve a minimum grade to unlock the last tier can make the fourth and fifth stages feel like a bit of a grind.

The co-op mode is also disappointing. Capcom scores points for throwing in proper online as well as local co-op play, but it's not so much a co-op experience as two players fighting on the same map at the same time. Compare The Mercenaries to FEAR3, Left4Dead, Gears of War 2 or even such flawed efforts as Army of Two or Kane and Lynch: Dog Days, and it's pitifully short of interesting ways to fight together.

It didn't have to be this way. Capcom could have built The Mercenaries out into a bigger game, with more maps, more classic Resident Evil locations and characters and more interesting mechanics. It could have taken more inspiration from Left 4 Dead, and turned it into a drop-in, drop-out horror shooter. Instead, we have that most distressingly familiar of 3DS phenomena; a £10 download title being sold for £30 to £40. And while it will doubtless sell more on the back of the included demo of Resident Evil: Revelations - a genuine 3DS Resident Evil chapter - the short glimpse you get doesn't tell you much more than (a) it's on a ship, (b) it will look brilliant and (c) it will have some nasty-looking zombie creatures in it. You're left feeling that The Mercenaries could have waited until Revelations appeared, and turned up as a bonus mode on that.