I did it! \o/ I'm so happy, after 5 hours trying, I could find a solution to the 8th step of challenge 2... It was about use time.Time function to don't let user's spam a game function. I already knew how to do something like that using Coroutine, but not using time.Time. The only tip I can do it's: don't think about code or how the right way to write it, just think mathematically! We already have the result of we wanted: a time delay. So, we need to understand how time.Time works (find it on unity's docs) and think a way to calculate or target value (delay). It's not so hard when you keep it simple... =) Again: Lesson learned - Keep it simple and think mathematically!!