Chase 'em down, string 'em up
Disclaimer: This review contains big words and actual english. If this seems frightening or overbearing, feel free to ignore this review, and refer to the average 3-line steam review of your choice. But if you do, you're pretty much a troglodyte.

Mark of the Ninja is a 2d stealth game by Klei, the same guys who made Shank and Shank 2. The same buttery fluid animations and art direction are present in Mark of the Ninja. Quite frankly, the game looks amazing in motion. Once you get the hang of the controls and the environments, you put whatever the current-gen protagonists of Assassin's Creed are called to shame. That's inadequate, you make the free-running elements in AC look like a geriatric with a crutches by comparison.

The story, so far (I've yet to beat it), is rather straight-forward stuff. You've gotten inked by your clan's tattooist Dosan, with ink which heightens your senses and gives you a convenient array of abilities that are mainstays in video games. But the downside is that the ink burns you out, and will ultimately drive you mad. So you've taken this Mark, in order to undertake a mission to safeguard your clan's existence.
And once you've completed your task, you're going to kill yourself.

Before that though, truckloads upon truckloads of henchmen are going to get theirs.
Alternatively, they will not even know you were there.

Klei made the Shank games. Shank games are 80-ish action homages as sidescrolling beat-em-up. MotN is the AC/Batman/Splinter Cell/Tenchu/Sneak-em-up treatment of a sidescroller. You have essentially complete freedom in how you choose to undertake your missions. And by how, I mean the level of lethality and bloodshed that will befall those who made the poor career choices that culminated in ending up on the wrong side of your blade. Or those ninja traps you will unlock or buy eventually. Or, you will just quietly slip by them. Hiding in doorways, behind potted plants, crawling past them on the ceiling, grappling from lamp-post to lamp-post above their heads, sneaking in the vents below or above them. The sneaking is really good. Like REALLY good, REALLY good.

Your equipment at first consists of firecrackers for distraction, a sword for stealth killing (kills are executed like a QTE, but not nearly as annoying. You press a direction and X to cut someone up), and that's all you got at first.
Later on you get a grappling hook, spike traps which work like land mines, smoke bombs and more fun stuff to play around with.

There are challenge rooms you might encounter (they look like gongs), which mix up the regular levels by being more of platforming challenges/puzzles. They use the normal game elements to complete, which manages to both freshen up how you think about the environments and traps/hazards in the game, as well as giving you a fresh lease on how to approach situations in subsequent levels.

I know a lot of game reviews fall prey to the pitfalls of hyperbole and similes, and I've already planted my foot firmly in that territory. And I kinda detest that. But honestly, it's impossible to do it when talking about MotN.

Hell, it's just straight-up amazing.

The stealth&stalk bits are great. The array of gadgets are groovy, as is the techniques you unlock with honor points as you complete levels. Some of them are different types of stealth kills, while another lessen the sound you make while sprinting, or allow you to string up dead guard from lamp posts in order to frighten other guards senseless. You can actually terrify guards to the point of them losing it completely, where they just start shooting wildly at everything they see or imagine they see. The only downside so far, is that sometimes it's a bit wonky whether you get the bonus for hiding bodies or not, and you might have to drop them a couple of times before it registers. Or possibly that's just left in there as a reference to Metal Gear Solid games. I'm not putting it past these devs, this is obviously a labour of love.

This is definitely a high-score type of operation, and I'm gonna come back to these levels.
You're scored on stealth kills.
You're scored on sneaking past guards closely while remaining undetected, and on distracting them.
You're scored on equipment kills, on terrifying guards (and the possible resulting friendly fire), and hiding bodies.

In each level, you can find 3 scrolls which tell the story of your clan and how it came to be, and what led up to you taking on the Mark in the first place. These also give you a point of honor each, which is used to purchase upgrades inbetween missions or at banner stops within levels.

There are also 3 seals per level. Seals are the same thing as optional objectives or challenges.
These seals fall into Path of Hunter, Combat, Nightmares or Shadow.
(Names subject to making-up by me, just now, seeing as it's late and I can't be arsed to start the game to be correct.)
Completing enough of these nets you new outfits with special pros and cons. For instance, the sneaky suit silences the sound of running feet, and allows you to carry 2 distraction items in your loadout. But the tradeoff is your sword.

• For anyone who enjoys 2d games with tight controls, this is a must.
  
• For anyone who enjoys cartoon violence, this is a must.
  
• If you've ever played a game that had a great single-player campaign, but was hamstrung by a forced multiplayer that was just put in there in order to sell the game to people who think singleplayer games are a waste of time, you need to get this in order to support the practice of making "great games that don't need no multiplayer".
  
• For anyone who played and enjoyed any of the stealth elements in any of the recent Arkham games, this is a must.
  
• For anyone who has ever daydreamed of being a ninja, this is a must.
  
  
  ...I just want slap a "MUST BUY" sticker on this.
  The rest of all the games I bought this holiday sale and have yet to play might turn out to be complete ♥♥♥♥, but Mark of the Ninja more than makes up for that possibility.