While around 90% of the DSiWare shop games are worthless pieces of junk that sap your money, there are some standouts that make the shop good.

One of these is:

Army Defender

Release: 2010

Cost: 200 Points

For the measely cost of 200 points, you get an extremely addicting defender style game with clever gameplay challenges.

You hold the DSi sideways, and keep your thumb on the top button (L for lefties and R for righties).

On the upper screen side, enemies will appear. These include:

Name / Number of pellets to kill

Solider: 1 Pellet
Jet Pack Solider: 1 Pellet
ATV: 1 Pellet
Jet: 8 Pellets
Helicopter: 8 Pellets
Paracute Solider: 1 Pellet
Cargo Plane: Aprox 4 Pellets
Tank: ??? (very high amount)

On the touch screen side is your fortress which you must defend using you machine gun.

Here's the catch:

The enemies appear in waves, but of two DIFFERENT colors. Using the L or R button, you have to switch your machine gun from red to green pellets, because they will only be destroyed if the colors match.

Each round gets longer by five seconds each time.

As you destroy enemies, you fill up your nuclear bar, which when filled, can be activated to destroy all enemies on the field.

Every thirty seconds, a carepackage, in the form of a cargo plane, drops a power up onto you that last 8-10 seconds.

Power Ups:

Flamethrower

Mine Balls

Rockets

However, if you hit the plane with either colored pellet, it will be destroyed, and you won't recieve the power up.

At the end of each round, aprox 25% of your health is restored, and you will occasionally recieve upgrades:

More pellets fired per tap

Adds more nuclear bars, and decreases the amount of carnage needed to activate it.

Increases Health By 10%

For such a small game, Army Defender supplies so much addicting gameplay, as well as a tutorial, the two levels of difficulty.
Army Defender is one of the best 200 point apps, and I recommend it!

9/10
-TM