Nano War is like the opposite of the Holy Roman Empire: it's a real-time game, and it's a strategy game, but it's most definitely not a real-time strategy game. Rather, it's a very simple concept packaged in a very simple game, which is entertaining for a little bit but rapidly loses steam thanks to its limitations.
The basic system of Nano War is very simple. You and your enemy are in battle in a field of circular cells. Cells controlled by your side will gradually increase in population, as will cells controlled by the enemy. There are also neutral cells, which are held by neutral troops; these don't increase in population over time. To attack an enemy cell, merely click once on your own cell and once on the destination cell; this sends half of your troops in the source cell (but you can click multiple times to send another half, and then another half of this, and so forth). Combat is settled by removing equal numbers of troops from both sides; the side left standing occupies the cell. (It is possible, though of course rare, for mutual annihilation to occur, in which case the cell becomes neutral.) It's also possible for two competing forces to encounter each other in transit, in which case the conflict is settled the same way. Larger cells on the battlefield produce more troops more quickly; each cell also has a maximum population beyond which it will stop producing more troops, which is higher for larger cells. Thus, the large cells tend to be the most important strategic points.
That's really all there is. While a pleasingly simple system, the problem is that there just isn't much to distinguish one level from another -- some may have more large cells, and some may have more small cells, but it doesn't really change the game all that much. This limits the game's long-term value. But the second problem is much more severe: because you are naturally much smarter than the AI, in order to make it a challenging game at all, the AI has to be given ridiculous advantages to start with. In the first few levels, the AI is still ridiculously passive, allowing you to defeat it with ease despite its huge starting advantage. Only around level 12 does it really begin being more aggressive, which can be quite frustrating given its still large initial advantage; you'll need both some luck and some skill to beat it at this point. But playing against an opponent on such unequal ground is less satisfying and more frustrating than it would be against a more competent and skillful AI, especially given the natural AI advantages of being able to coordinate multiple movements more effectively than you can hope to.
I believe I've described many games here as "brightly colored", but this might be the first time I think a game is too dimly colored -- both your color and the enemy color are kind of washed out, and if you're in a real hurry it may be difficult to distinguish the color of a small, heavily-contested cell. The music is a little spectral, and kind of creepy, but it's not bad, either; the sounds are pretty basic.
Anyway, while the underlying concept in Nano War is rather nifty, the poor AI and the simplicity of the concept mean that this just isn't a game which is good for long-term play. Currently the game has 14 levels, which is already the point where it begins to drag. Getting the badge wasn't too bad, but I wouldn't want to have to play significantly more than that.