This sounds very interesting.

What do you mean by "3rd quarter" snow? At first I thought that it was about school; then about the "cycles" of the planet, but elsewhere you didn't divide the seasons into quarters.

Here you used a repeated word where it'd sound nicer if your substituted 'it' for 'planet' the second time."the sticky purple slush that coated the planet's surface for half of the planet's cycle."

Quite good concretion of the world with details like the third leg and the constant use of time "units". Also, the dare and the use of the slang "PM" makes the alien culture seem real. The thing about the genders is logical. However, does that explain why Razae and Mokku look so different from each other?

Ew, the watcher is creepy. But why is it going after them now--did they not have "ten units" untill Curfew? Perhaps make the time more pressing.

Very creepy. Not with a huge impact, because the Humans and Controllers both were rather vague, but this is a good story and with polishing, I think, could be submitted to a magazine.