My favorite blast from the arcade games of the past lives again in the iPhone’s App Store. Galaga remix is a decent recreation of the original, plus a 21st century version, perfect for wasting time and enjoying it the process. Macworld’s review:

Galaga was the sequel to Galaxian—a next-generation Space Invaders, if you will. The screen swarms with waves of insectoid alien spacecraft you must shoot down with your space fighter. Galaga built upon its predecessor by introducing more colorful aliens that flew about the screen in eye-catching (and dangerous) patterns, along with bonus waves and a “dual-fighter” power-up that let you rescue fighters captured by alien motherships, to double your firepower.

$6 or free in the Lite version.