[SzczerbiakManiac]

I just stumbled across Grow Tower and found it quite entertaining. Part of the fun is figuring out what you're supposed to do in the first place, but here's a small clue. Hover over red up/down triangles. See that light bulb thing at the top?

It doesn't have much replay value (unless you just want to watch the animations again), so it's not a giant time-waster.

Need more of a hint?

Spoiler:

You're trying to turn the sun on. To do so, you have to build a tower up to that level. Select one item at a time from the menu on the right. Items will/may interact with each other, so the order you place them is crucial. Experiment with placing things in different orders, observe what happens when you place additional things, then see what works best.