Hang On to Your Marbles: Bonsai Blast for Android Is Hours of Fun
Bonsai Blast is hard to categorize. It's sort of a puzzle game, but timing, speed, and aim are every bit as important as strategy. On each level, multicolored marbles come rolling in on a track, slowly heading toward a black hole; if they reach the hole, you lose. You control a marble-shooting turret, and your task is to shoot into the train of oncoming marbles, matching three or more of the same color to eliminate them. You get extra points for creating combinations and longer chains.
As the levels progress, the path the marbles take becomes increasingly intricate. Sometimes they wind around themselves, making it very hard to hit the one you want. Other times they come in from multiple places simultaneously. And still other times you can hit them only by bouncing your marble off a wall or shooting it through a pipe. The backgrounds are pleasant, and are designed to look like Zen gardens, which is a nice effect. The game offers 90 levels, and they get extremely difficult--but at no point do you feel that your attempts are futile and you're wasting your time.
The creators of Bonsai Blast do a good job of changing up the game to keep it from becoming repetitive. Eliminating a marble while it's flashing triggers either a special ball (such as a fireball, or a ball of light that destroys everything around it) or an overall effect (such as the marble train rolling backward in the track a ways, or falling rain that destroys some random marbles). You'll really need these power-ups to get through the more advanced levels.
The only negative thing I can say about this game is that I've definitely played others like it before. Luxor Quest for BlackBerry is one, and I seem to remember other Flash-based versions. That said, Bonsai Blast is the best implementation of this type of game that I've seen. It crams in a ton of value (especially for a free game), and I highly recommend it.