Stealth games have a creepy cousin in the survival-horror genre. The relation manifests in an oppressive environment, which isn't clearly designed or signposted to let the player succeed as easily as he would in a spectacle-driven action game. But while horror is really about conserving quantifiable resources within the claustrophobic confines of an inhospitable world, stealth games expect you to wisely expend your movements and other reckless displays of presence. When it comes to guard patrols and impenetrable installations, as you'll see in XBLA's Mark of the Ninja, your currency is quieter and more abstract.

"In a stealth game you're fundamentally undetected. The world is just kind of running and it's on the player to poke and perturb it after observing it for a bit, and you can just do a lot more interesting things there," says Nels Anderson, Technical Designer at Klei Entertainment. To think of the world as an unpredictable beast, one that might bite off your finger if you prod it in the wrong place at the wrong time, might be a good way to understand the polarized, frustrated relationship some players have with the stealth genre.

According to Anderson, "the power dynamic that almost always falls out of that, to make that work, is that interplay between strength and weakness." Having the chance to study the environment and enemies is a huge advantage, but acting on that information can lead to failure. There's an expectation of perfection - I was spotted, so I have to revisit the last save and do it right! - yet a severe punishment of practice. Anderson thinks of it as a "gulf of execution," one that he thinks Mark of the Ninja can fill.