Smakus's take:

N+ is a game I had never heard of before the XBLA release.  It was getting a lot of buzz so I knew this title would be something worth checking out.  After trying out the training levels, I knew there was enough substance to justify a full purchase.  I'm glad I bought it... in a nutshell, this is the perfect XBLA game.  Read on...

Overview:

In N+, you play a little ninja who has a limited lifespan, and the basic goal is to find a switch, which unlocks an exit door.  Reach the exit door, and you make it to the next level.  Go through 5 levels within your 90 second lifetime, and you can progress to the next set of levels.  You can extend the life of your ninja by collecting gold, but there are also many obstacles and enemies to avoid along the way.

Gameplay (single player): ★★★★★

The great thing about this game is it is very simple.  There are essentially 2 buttons, and you use the left stick for movement.  One button jumps, the other commits suicide.  Seeing as how suicide makes it pretty difficult to beat the game, you'll be doing a lot of jumping instead, and luckily, they got the jumping just right. 

One of the reason why Super Mario Bros. was such a great game was due in part to Mario being such a good jumper.  It felt good to jump Mario around the screen, off of ledges, and onto boxes.  They just nailed the feeling.  N+ feels good in nearly the exact same manner.  You can give the jump button a little tap, or you can hold on to it for some really high and spectacular jumps.  But the jumping isn't all that is right with N+.  The feeling of momentum as your ninja builds up speed for longer jumps, wall jumps, or even just sliding down walls feels great.  The animation is very smooth, and conjures memories of the original Prince of Persia, mixed with a little Ninja Gaiden.  A cross of Mario, Prince of Persia, and Ninja Gaiden?  Count me in.

The levels start out pretty simple, but ramp up in difficulty as you progress, introducing various enemies and obstacles you'll have to jump, cling, slide, and run around.  Due to how your ninja runs and jumps about, coupled with the simplistically perfect physics, this game is just plain fun.  Should you die and untimely death, you get unlimited lives with which to retry the level.  At first it is easy to complete the levels before running out of health, but as you progress, the gold becomes an increasingly rare commodity, and you'll have to budget your time accordingly.  Take too long, and you won't have enough health to make it through the last level, no matter how much gold you find.  And speaking of death... Well, i won't ruin any surprises, but lets just say the deaths are very satisfying and further demonstrate how cool the physics are.

For the single player campaign, there are tons of levels, and some of them are quite difficult, requiring perfect jumps and timing.  N+ supports downloads of more levels in the future, and even has a complete level editor for creating your own rooms to navigate.  With these options there is more than enough bang for the buck on the single player front.  But the multiplayer is where this game really shines...

Gameplay (multiplayer): ★★★★★

With up to 4 ninjas split-screen OR over Xbox Live, this game is poised to become an XBLA classic.  There are only a few modes of online play and the most popular are likely to be the race and survival modes.  These modes are deceptively fun, and you can't help but play with a smile on your face.  Imagine 4 ninjas tearing jumping, sliding and tearing around the level trying not to die as they all rush for an exit.  Only one can make it, and it is always inevitable that one ninja hit a mine, only to set off a chain reaction of destruction as bits of his body ricochet around the level.  This unpredictability makes multiplayer great fun, as the one who controls their ninja the best doesn't always win.  It's good times, and since multiplayer allows you to use your own custom maps (or partake in those of others), this game will have near infinite re-playability online.

Graphics: ★★★☆☆

It doesn't get much more plain than this.  But at the same time, the graphics are perfect.  The joy is in the simplicity of this game, and graphics are representative of that.  The effects and animations are done very well, and there is no disappointment in this simplicity.  There isn't much variance in color, and definitely no fancy backgrounds, but this game needs neither.

Sound: ★★☆☆☆

Totally simple sounds, however they are perfect for the game.  The gold-collection sound  effect overpowers the others a bit, but it doesn't get annoying.  You might find yourself turning down the soundtrack a little if you want to hear some of the more subtle sounds, like sliding down a wall.  These are great sounds, so be sure to try that. 

Soundtrack: ★★★☆☆

Now, speaking of the soundtrack... it is 8-bit electronica perfection.  Very catchy, very retro, yet at the same time updated with a modern electronica feel.  Great use of stereophonic syncopated 8-bit beats, and it never gets old.  That being said there isn't too much variance here, so if you hate techno, etc., you will be making good use of the Xbox 360's ability to play your own tunes.

Projected Longevity: ★★★★☆

There will no doubt be dozens of user-created levels flourishing over Xbox Live that will perpetuate the life of N+ for some time.  I'm waiting for the inevitable YouTube videos of multiplayer madness and ninja destruction that is bound to take place, similar to the kinds of things you see going on with Halo 3's Forge.  They didn't have to include a level editor for this game, but they did, and that alone will extend the life of this game 10-fold.  That being said there isn't too much variance with what you can do with custom maps, but the creative types will be able to crank out some wonderful stuff.

Overall: ★★★★★

N+ represents what the perfect XBLA game should be.  Something you can play for 5 minutes, 5 hours, or anywhere in between.  This is an arcade game, and if you keep it in context, you can' help but love it.  A mix of action, strategy, puzzle, and platformer, with no elaborate button layouts to memorize, and feel-good physics.  The controls and levels are simple enough for anybody to pick up and run with, but there is enough challenge in the latter levels to keep the hardcore gamers interested.  I can see this game being very popular in households that have gamers of mixed interest and skill.  There is something for everybody here.  Get tired of the multiplayer levels?  Make your own with the editor!  Perfect gamer bliss.  Try the demo, and if you aren't hooked by the end of the training missions, I'd be very surprised.