Ikaruga memorably included a color-switching mechanic, where players could absorb bullets of the same color. Thanks to clever design, it quickly became a beloved classic. The PC port is based on the Xbox Live Arcade release, but there's new features added specifically for the Steam release.
The PC release includes support for Steam achievements, leaderboards, and cloud. However, a recent update from Treasure also promises eventual support for Steam trading cards.
Being a decade-old game, the system requirements are quite lax, requiring a Windows XP system with 1GB of RAM and an Intel Core2 Duo processor (or Athron64 X2).