Pollka (Easy) (Basically Cheating)

Warning!

This guide is effectively cheating, so if you just want it for the achievement, then go right ahead, however if you want to experience the game as it was intended, then this is not the place for you.

How to Perform This

The trick to this is very simple, we are abusing the lack of color changing to our advantage here. For this to work you need to go to your settings (I recommend taking a screenshot of the original settings so you can revert them when you're finished) change every number in the first 3 sets of brackets to "0, 0, 0" while changing nothing else. then, you can do whatever you want for the last color, but i recommend "355, 355, 355" which is the RGB value for white. Now all your colors will only be black and white, meaning when you can retry the level until you get the white background, and it is much easier to shoot them and not the friendlies, because they all look the same.

Disclaimer

For this last part, i recommend going into the level normally in practice mode (hit "q" on the keyboard) to get a feel for the level, and to understand how the enemies/good guys move

Ending

For the end of the level, it is a bit of educated guess work. Once you have gotten through the tough part, the colors will change, and lines of good guys will come down very quickly with a very slow bad guy behind them, there will be some white good guys that come down with these lines, which means guessing when to shoot is easier. Do not wait too late or the bad guy will reach you, but don't shoot too early or you may shoot an invisible good guy. Because the colors have changed it is guaranteed the bad guys will be invisible, because they will be the same color as the background, so you have to guess a little bit.

End

I hope this could help you on your achievement hunting endeavors, happy hunting!