Mr.Ninja takes a well-worn gameplay formula, the endless runner, and puts a unique twist on it by making scoring almost an unnecessary element. I mean, if you want to accomplish anything in the game other than running forever, you'll need to score, but in Mr.Ninja, simply running won't get you any points.
Whereas other endless runners give players some sort of score or sense of accomplishment based on how long they survive, Mr.Ninja demands that you chain together combos by "slicing through" all of the enemies that are lined up along your endless run. You don't even have to actually do any slicing. You simply have to jump into their path.
While that sounds simple, the game sets up some pretty outrageous lines of enemies for you to follow if you intend to keep your combo score going. While you're free to miss as many enemies as you like, the combo multiplier resets every time you miss even a single one, making it much more advantageous to make your jumps as patiently as possible, which can be difficult, given how much fun it is to jump from odd platform to odd platform.
Visually, Mr.Ninja is subdued. It's not filled with different colors, but has a very specific visual style that suits the gameplay well. Many endless running games, Mr.Runner comes to mind, seem to latch onto these simplistic visual styles, leaving the emphasis on the hurried gameplay. Mr. Ninja does the same, though I think the oranges look a little better than the black and white of Mr.Runner.
If you enjoy endless-runner-style games, Mr.Ninja is an absolute blast. Keeping your combos going is an exciting and challenging experience, and well worth the price of admission. Mr.Ninja doesn't exactly reinvent the genre, but it sure does it proud.