Stylish, addictive, and clever.
N's gameplay is a simple platformer style, but more puzzle based - there's action, but you dont defeat enemies, you avoid them. You have a 90 second lifespan for each "Episode", which consists of 4 levels. To extend this lifespan, you can pick up pieces of gold that extend your lifecycle by two seconds. It's simple, challenging, and, yes, sometimes very frustrating, but it's a lot of fun.
The graphical style is simple, there's a bit of colour here and there, and most things are made up of simple shapes. However, it can run incredibly smoothly, and the animations are fluid, even if they're simple.
Sound - Pretty basic. Not too much, no music, but it's not necessary.
Value - 10/10, easily. One can't complain about value in a free game. Still, N is exceptional in this aspect.
With hundreds of levels, and a level editor, N's replay value is insane. It'll take you hours and hours to get through.
N is a clever, stylish game, and it's not to be missed at any cost, considering just about anyone has access to it.