Sinister Planet – Free Amazon Appstore App of the Day 7/16/11

Mission Objective
Your objective is to attack and destroy a series of alien worlds, progressing toward the ultimate challenge: Planet Sinister. To destroy each world you have to attack the surface and take out the power grid protecting the planet’s core. To aid you in your quest, you have the opportunity to upgrade your ship’s weapon systems by collecting power-ups (in Arcade mode) or amassing gold (in Battle mode).

As you progress through the waves, you will find yourself needing those upgrades as more deadly enemies are introduced. Upgrades available include extra laser pods to double or triple your firepower, ECM attacks (aka Smart Bombs), turrets for 360-degree shooting, and more.

Make little ones out of big ones
Collect the Gems
To make it through each wave, collect the gems produced as you blast the asteroids out of the sky. Don’t worry, the asteroids won’t hurt you, but you will face a different challenge–your enemy just loves to grab those gems too. Make sure you reach them first, and shoot them quickly, or they will be transformed into much more dangerous foes.

As a welcome respite from the hard-core destruction, you get the chance to gain bonus points by completing the challenge waves. Aliens will fly in formation around your ship while you attempt to execute a complete wipe-out. It’s not easy, but getting the right upgrades will greatly aid your mission. During the challenges your ship gains temporary indestructibility.