Another classic video game console celebrates a milestone this week.  Sega's Dreamcast was released in North America ten years ago this past week, on 9/9/99.  Though the console was short lived, it has developed quite a following, even a decade later.  Many features of the Dreamcast were ahead of its time, most notably a standard modem and internet support allowing online co-op for the first time on a home console.  To celebrate the 10th birthday of Sega's final console, we'll take a look at some of the best co-op games the system had to offer, as submitted by staff and readers. The Shoot 'Em Ups

For non-Ikaruga fans, the game's core concept is that the color of your ship determines who can damage you. If your enemy is the same color as you, your enemy's attacks won't damage you (in fact you can absorb their attacks). And inversely, if you and your enemy are different colors, their attacks will damage you.This is where the color-changing aspect comes into play.