Love the colors and old school pixel art style. The switch of music really fits well with the different worlds.
Only thing is I feel like the world without the enemies is a lot easier. Just needs a little balance between the two.
Thanks for the feedback. Yeah the alternate world is easier. I tried with increasing the maximum size of the objects, but then they often became too big, so that there was no open path. I tried to make the first world more appealing by giving 10 points per killed enemy, so you can quicker farm points there (if anyone wants to reach the 9999 score).