Added:

• Split-screen co-op (xbox gamepad + keyboard/mouse)
• Bot assistant (it helps you after "Score 500 points!" achievement is reached. It's not so smart but it can help you)
• Player selection menu (skin, control type)
• New soundtrack (Awesome Force)
• New enemies (including elites)
• New bosses
• New weapon (plasma blaster after 2nd boss instead of disintegrator)
• Voice announcer
• New palettes
• New logo
• New features
• New animations
• Updated some sprites
• Updated game mechanics
• Cheats

Enjoy your stay!

And don't forget to post bugs here if you find some.