Algodoo

Welcome back, decipherer. It seems as though we have been the target of another broadcast. Strangely, this one was in a PNG format, suggesting that whatever sent it to us has studied the compression algorithms in human computers. The source of the tramsnission appears to be closer in proximity than Proxima Centauri, meaning the alien creature or alien machine that generated and sent the image may be rapidly approaching. We must quickly determine whether this message is a threat or an attempt at interstellar cooperation, and you are our only hope!

Put all guesses in the comments. Don't read any comments unless you want to risk spoiling the puzzle for yourself.
Good luck scholars!