In Skylanders: Spyro’s Adventure, the only way to unlock an additional playable character is to drive to a store and purchase a new action figure. Since retailers cannot keep these figures in stock, adding new members to your team is the most difficult challenge the game offers. In Skylanders: Cloud Patrol, a fun shooting gallery developed exclusively for the iOS platform, characters are unlocked in an interesting, new way: by playing the game.

To add a new figure to my collection, all I had to do was tap the screen to fire cannonballs at trolls. After just 20 minutes, I earned enough in-game currency to purchase two new monsters of my choosing. Familiar faces like Wrecking Ball and Whirlwind are part of the cast (along with the rest of the 30 original Skylanders), but you can’t unlock any currently unreleased characters at this time.

What good are the characters once unlocked? None, other than looking adorable and rewarding you with twice the gold if their elemental association syncs up with the element of the day.

All of the Skylanders fire the cannon in the same way. Tapping the screen fires one shot, while sliding a finger along multiple targets creates a chain combo that produces a gold bonus. The gameplay is simple in scope, and doesn’t deliver more than a few minutes of fast-paced fun.

The screen is often cluttered with movement. Sheep bounce across it, trolls jump in and out of cover, and bombs float ominously in your line of vision. If you accidentally touch a bomb, it’s game over. Once all of the trolls on a screen are cleared, the game transitions to another screen with a different formation. Most of these screens can be completed in a few seconds. The rotation of screens is endless.

Cloud Patrol doesn’t tell a story or take players to different lands. The sole purpose of playing is to earn more gems and currency to purchase new characters and magic items. Here’s where things get weird -- if you already have a collection of figurines for your PS3, 360, Wii, or 3DS game, you can enter the web code that comes with them to unlock these characters in Cloud Patrol. That defeats the purpose of playing the game, but if you want them immediately or would rather waste time entering codes, you can do that.

I had a good time playing Cloud Patrol for a few minutes here and there, but I could never see myself playing for extended marathon sessions. That addictive “one more game to improve my score” quality isn’t there. Your progress in Cloud Patrol has no effect on your Skylanders console experience. This title misses numerous opportunities to add more depth and incentives to keep playing, making it feel like a simple cash-in on the Skylanders name.

Skylanders: Cloud Patrol is available now in Apple’s App Store for 99 cents. This review is based on version 1.1.0. The download is 78.2 MB. The game is rated 9+ for frequent/intense cartoon or fantasy violence.