Not bad
Very fun to play although I don't get why this version didn't have the music.
I liked the look of the game; Very colorful. Also the up-grades made it last longer.
It was a bit too easy though at first because you could just stay at one point and shoot anything on the screen. The powerups gave you a reason to move though and it did get a bit harder later though.
So it was a good and fun retro game, but a lot better with the music.