I think the best way to summarize Scurge: Hive for the Nintendo DS would be to liken it to a top-down, isometric RPG version of a Metroid game, though definitely not as good. The main character is even a female space bounty hunter in a special suit, sent on a dangerous mission. The fact that I use the phrase 'not as good' should clue you in to the fact that, though this game is decent to play from time to time, there's nothing really special about it.
In Scurge, you play the role of Jenosa Armad, a female bounty hunter. You're sent on a mission to investigate what's happened to a research laboratory that sent out a distress signal moments before being cut off. Since there's an infectious presence in the laboratory, you're issued a prototype suit that prevents the infection from taking over your body too quickly, and aside from that, you've also got your computerized onboard AI Magellan to help you out.
As mentioned above, the gameplay is an isometric pseudo-adventure title. Jenosa runs around shooting aliens and jumping to and fro. Most of the game is spent running around levels, collecting the odd power-up for your suit and gun, levelling up, and powering nodes that allow you to teleport around the base. Often, to proceed through some doors, you'll need to search the available area for a number of keycards, which let off a pinging noise when you're in the same room as one. A lot of time is spent collecting these.
Eventually you'll find that there are basically three types of creatures that would like you to die. There are also three types of weapon that you'll find along the way that you can use to deter them from completing their goal. Use a fire weapon against a biological creature, for example, and it'll burn right up, but use it on a robot and you'll find that contraption even stronger than before. Switching through the weapons is quick and easy, and though it feels like it slows things down at first, it's easy to quickly get into a rhythm of bringing up the weapons menu, selecting the best choice for the task, and blowing away the enemy before switching again.
Speaking of things getting stronger, there is an RPG element to Scurge: Hive, albeit a miniscule one. As you defeat enemies, they release green globules that gravitate close to you as you approach. Get enough of them, and you level up, raising your amount of HP and making your shots just a little bit more powerful. It's a decent mechanic, though simple, and though it seems added on for no particular reason, it doesn't detract from the gaming experience. Besides, who doesn't like to see their characters become stronger?
A big part of the gameplay also involves the fact that Jenosa is slowly being infected. The key to the Scurge lifeform is that it can infect nearly anything, be it mechanical, biological, or just made of energy, which is why the entire research lab has been taken over by it. The only reason Jenosa isn't controlled the moment it comes into contact with her is because of the suit, which somehow protects her against its dangers. But only slightly. No matter where you are, an infection meter slowly builds at the top of your interface, going from zero percent to a hundred. When it reaches that point, you start to lose health, and quickly. The only way to bring your meter down is to visit decontamination points scattered throughout the various levels of the game, which conveniently double as save points.
This is the mechanic of the game that's most annoying. What it does is basically time the amount spent outside of the save points, which heavily discourages taking a look around and sightseeing (though, granted, there isn't a whole lot to do besides shoot stuff). Sometimes you'll be locked away from any possible save points like during a boss battle or a lockdown, and you're essentially out of luck. And nothing is more irritating than dying during a boss battle simply because you just ran out of time. There's even a red fungus-like covering on some of the floors of the game that accelerate this infection while you stand on it, and that doesn't help at all.
At first, the game seems pretty fun. Like it was said before, it resembles a sort of Metroid-esque style of gameplay. Well, it does at the beginning, at least. Though the core gameplay is fairly solid, enjoyable, and easy to pick up and play, the rest of the game quickly becomes repetitive. It's easy to see a basic formula in every level you get to: find the nexus, find a power-up used to explore the entire level, unlock the nexus security nodes, fight the boss then proceed to the next level. After a while, it just gets boring when you realize you're essentially going to have to repeat everything you've just done, only the enemies will be a different color and the landscape will look a little different. Since the main core of the game, shooting enemies and running around, is pretty good though, it's still playable. It just gets a little frustrating. Also, a slight issue is the controls. The game deals with isometric 3D-like graphics, but with 2D controls. The result is that there are only eight ways to shoot, but the enemies don't always approach in straight lines from these eight directions, so aiming can be a concern at angles. You eventually get the hang of it, but it's still an odd design choice.
The game is repetitive, the story thin and linear, and the infection mechanic is an annoyance, so why play Scurge: Hive? Well, underneath all that, the game is simple and fun when you just want to shoot stuff. The story is kind of pointless and just a reason to move things along, but multiple difficulties and some unlockables allow you to play it again, if you so desire. It's a decent action/adventure title; just don't expect it to be any more then that.