If you think stealth games are still stuck in a rut, you haven't played Mark of the Ninja yet. It does exactly what a stealth game should do, giving you a wide variety of tools and abilities with which to conduct your stealthy business, and gracing you with the absolute mobility to actually use them. Too many stealth games depend on rote memorization of enemy patterns and more or less go to shit every time you trigger an alarm, but this one, by contrast, empowers you to toy with the enemies like a stealth god, and still ably disappear unscathed back into the shadows even when the lights come up. You know that feeling in a stealth game when everything feels like it goes just your way, and you clear a whole room of witless guards without so much as a sound? I haven't gotten that feeling since Arkham Asylum, but Mark of the Ninja has it. That's the highest praise I can think to give this game.
The designers at Klei made things easier on themselves by smooshing Mark of the Ninja's action down to two dimensions, which naturally gives you less spatial data to process than a 3D scene and consequently helps you maintain a more confident feeling of control over everything around you. For instance, it's a lot easier to predict enemies' line of sight when they can only be facing one of two directions. But it goes beyond that. As a bonafide ninja, your mastery of the environment is total; you can climb up walls and across ceilings, duck into ventilation ducts, dart between cover, and grapple all over the place faster than guards can possibly keep up with you. The game simply wouldn't work if you weren't so incredibly nimble, and it's that basic control and mobility that makes this game as fun as it is. It also helps that you can pause time whenever you want, to quickly queue up multiple abilities which then play out as soon as you resume the game.
The design of the game is eminently impressive at every layer. On top of the core movement, you've got a wide array of abilities that let you focus on very different styles of play. You've got a category of distraction items like a noisemaker and chemical flare that are useful for getting enemies right where you want them. Then there's an attack category that includes stuff like spike traps and ravenous, flesh-eating insects, in case you'd rather just murder everyone directly with your tools. Or you can just rely solely on your trusty sword, since there's a whole list of stealth kills that let you take out guys while behind them, while in cover, while on the other side of a door from them, while hanging above their heads... This focus on multiple play styles reaches its peak with a series of unlockable ninja outfits that dramatically improve your abilities in one area (say, letting you carry two distraction items at once instead of one, or speeding up the process of stealth kills) while hampering you in another area (for instance, preventing you from restocking your items mid-level, or taking away your sword entirely). So if you want to go all the way in one direction, you can.
The game even rewards you if you want to do none of this, since the single biggest bonus you can get at the end of every level comes from not killing a single enemy. There's an exceptionally elegant three-way objective system in place, with three types of objectives and three of each type per level (for a total of nine). Three of these are simple haiku scrolls hidden in the level, which dole out little bits of story as you go. Another three are level-specific objectives that push your stealth abilities. And the last three are tiered score objectives, the first (and probably second) of which you'll get as a matter of course. Getting the high score objective on each level requires you to really use your abilities to the utmost, though, and since you get points for practically every positive interaction with a guard--distracting them, terrorizing them, slipping by them unnoticed, hiding them after they're dead--you're encouraged to tackle each scenario as thoroughly and elegantly as you can for maximum score. I was immensely gratified when I started nailing all nine objectives (which result in more upgrade points on the skill tree) in each level about halfway through, but the game isn't shy about ramping up the difficulty in meaningful ways. You'll still be running into crazier types of obstacles and more well-equipped enemies all the way up to the last couple of levels of the game.
Klei sort of established itself as the fluid hand-drawn 2D art studio with the Shank games, and while those games looked great and moved with style, the depth of gameplay wasn't really there to keep them totally interesting all the way through. Mark of the Ninja makes good on that potential for marrying beautiful art and engaging design, with in-game action and hand-animated cutscenes every bit as good as the Shank stuff. But this game could use stick figures on blank backgrounds and it'd still be a ton of fun to play. It's so rewarding that, time permitting, I'd love to go back and get every objective on every level, and also finish its new-game-plus mode; in other words, I'd love to do everything there is to do here. I can't say that about many games. Mark of the Ninja executes its formula to such a high degree of near-perfection that I could hardly think of a way it could be meaningfully improved the whole way through it.