Well done on finishing, I can't get past level 16, even with the hint above!! I can get the white balls home, but can't figure out how to get the yellow ones home. I tried a similar route to the whites but built the blocks up higher hoping more invisible blocks would appear above the twin spikes next to the white cage, but it didn't happen, d'oh!
Hi, the yellow balls follow the same route as the white ones, except the fact that you have to remove the blocks before the white gate and let the yellow balls fall on the floor below. Gather the balls and move them on the left: go upstairs and then reach the yellow gate on the right. Let the balls fall from above on the gate. Either way, you've already done the hardest part!
Thanks for playing Planet Balls. It took some effort both in implementation and in the level design and your appreciation pushes indie developers like me to do more video games. The later levels are challenging and sometimes it's necessary to make the balls cooperate with each other.
However, this game didn't have a big spread, I think mainly because it was not distributed through some game publisher, but I prefer to remain a 100% indie developer... ¯\_(ツ)_/¯