I like the idea, but I feel like the game is too hard? I think it could be made more enjoyable by increasing the player speed or by extending game area. I died at least 10 times in a row trying to figure out the player movement.
Also I am not sure if this is intentional or not but when the "Choose!" menu shows up, the player isn't actually required to choose a color since shooting is still allowed and when the current color is white, it is actually better to not choose anything. Levels 2 and 4 can be beaten this way by shooting white bullets to both enemies.