As a prequel, Dead Space Ignition attempts to fill in some background on events that transpire on the Sprawl, a massive orbital mining station that serves as the setting for Dead Space 2. For narrative purposes, Ignition uses comic-book-style panels that feature Franco and Sarah, an engineer and cop (respectively), who are sent on a wild-goose chase to deal with numerous malfunctions and mishaps occurring on the station for no discernable reason. Each story sequence is bookended by a minigame that represents Franco hacking into one of Sprawl's affected systems. There are three minigame types to encounter, and they change and become more difficult to solve as the necromorph infestation comes to light and takes over the station. Unfortunately, there's nothing remarkable about either the story or gameplay of Ignition.
In terms of story, there's no clear reason why you should even care about Franco or Sarah outside of some light bantering between the two that adds minimal depth to their relationship and character. Much of their presence in the scenario falls on being in the wrong place at the wrong time, so their dialogue eventually devolves into typical horror mainstays as they go from place to place, avoiding necromorphs. It's also telling that a major plot twist between the two characters makes almost no sense in the context of their relationship and that the method through which the twist is carried out is more shocking than the result of the act itself. Additionally, it doesn't help that the voice acting is substandard and often doesn't reflect the drama depicted in the cutscenes. These characters seem awfully calm for being perpetually two seconds away from death by space zombie.
The three minigame types in Ignition aren't terrible, but there isn't much to them. The first type you encounter is called Trace Route, which is a race where you have to guide Franco's hacking line through a series of obstacles while competing against security measures that are either trying to obstruct your path or beat you to the finish. The tracks become more difficult as you progress through the game, adding new types of barriers, enemy security measures, and pick-ups that reverse your controls (making down up and up down, for example). The most egregious problem with this particular minigame is the rubber-band AI. No matter how well you're doing and no matter how well you use your own power-ups, which include a speed boost and a barrier to slow down the AI, you are never in the clear until the final seconds of the race when it's obvious that the enemy lines can't catch up.
The second type of minigame, called System Override, is a reverse tower-defense game where you send viruses on a path to the core. Naturally, the core is protected by antiviruses (serving as the towers) that can detect and destroy your viruses. The trick is to use the four virus types at your disposal (though only two are available at the start) to distract and destroy the antiviruses. This is perhaps the easiest of the minigames--even in its later, more difficult forms--because once you find a path (by taking a few seconds to look at the map), it's only a matter of time before your viruses overwhelm the computer's defenses and make their way to the core.
The last of the minigames is Hardware Crack, and it's the most frustrating of the three. Unfortunately, that frustration doesn't come from the way the puzzle is designed, but rather from minor annoyances that continually stack on top of each other. The goal is to guide energy beams on a circuit board using deflectors while making sure that the color of the beam matches the designated item and direction on the board. The issue is that the rules governing how the beams behave isn't clear, leaving a lot of guesswork in solving the puzzle when you encounter it the first and second time over the course of the game. Add to that a supremely annoying clicking noise, cluttered visuals, and an unnecessary time limit, and you have the makings of a genuinely irritating minigame.
All of these minigames have a two-player local multiplayer component that has varying effects on the entertainment value of the games. Trace Route benefits the most, since playing with another human alleviates problems associated with rubber-band AI. System Override is a bit of a mess, however. One player takes control of the viruses while the other faces the task of placing antiviruses, but the player controlling the antiviruses doesn't have enough time to set up adequate defenses before the attacker starts playing and is able to start destroying them with bombs. And finally, Hardware Crack's multiplayer component is just flat-out confusing as a turn-based competitive game where players can remove each other's pieces or block energy beams. The time limit often makes it difficult to make any progress.
Ignition culminates in unlocking a new costume for Isaac Clarke that will be available when Dead Space 2 arrives. You won't have much trouble receiving that award and doing so in quick fashion, since it takes only about 40 or so minutes to complete everything on your first try (and even less time to play again to check out the branching story), which ultimately makes it feel like you're paying 400 Microsoft points for a costume unlock. Aside from that, Ignition's story and minigames fail to add anything worthwhile to the Dead Space universe.