Ninjump is essentially a climbing game in which your ultimate goal is to climb up the sides of two adjacent buildings, leaping between the two in order to avoid or destroy the obstacles in your way so you can get as high as possible. You'll run up against Squirrels, Birds, Ninjas, who throw Ninja Stars or Dynamite, even the various awnings and overhangs that decorate the higher ends of the buildings can knock you off to your inevitable, tiny-ninja doom.
The gameplay is simple enough. Tap the screen to make your ninja jump from one building to the other. Everything else is taken care of for you. It's on these jumps that you take out your obstacles to gain more height. The gameplay also allows for boosts of distance to be covered. If you take out three squirrels in a row, for example, without taking out any other obstacles, you transform into a mighty squirrel-ninja and leap, bound and frolic up the side of the building for a short period of time, completely invulnerable.
I can't stress this enough. One hit and you fall. No ifs, ands, or buts. Your choices are to avoid the obstacles, or plummet from the sky (with a relatively amusing scream, no less). Unless of course you come across a force-field. Force-fields are represented in the game as small, glowing blue orbs that, if you run over it, you are engulfed in its blue-ness. This is the only way that you can take more than one hit and continue up the side of the building. With a force-field activated, it basically gives you one free pass to get hit. When you get hit with the force-field up, it disappears and you are back to your regular, vulnerable self.
Overall, the aesthetics of the game are mostly pleasing. The graphics are delightfully cartoony, bordering on adorable. The music blends modern techno with the charm of an old kung-fu movie score and the easy controls make for the ultimate casual experience. The sound effects are simple, but effective and the sparsity with which they're used adds to the experience. The game does tend to run a little choppy on my phone, and that can take away from the experience, but I run an old school 3G and it really only gives me problems when I haven't turned my phone off and on again in a day or so.
It's a free download, so no harm, no foul there, so long as you can put up with scrolling advertisements at the top of the screen.
At the end of the day, is Ninjump worth the download? I gotta go with Yes, on this one. It's a great casual game and if you spend any percentage of your day on the bus or subway, or waiting for the bus or subway, it's a great and addictive way to kill the minutes until your arrival.