Despite the growing popularity of teaching children to program games, little is known about the benefits for learning. In this article, the authors propose that game mechanics can be used as a window into how the children are thinking and describe a strategy for using them to analyze students' games. The study involved sixty 10-14 year old students in the US who spent 10 hours learning to use the Alice programming environment, and 10 hours designing and creating their games, alone or with a partner. Forty games were coded for five game mechanics that require the programmers to think in ways that are dynamic, time dependent, or complex. The results describe the mechanics that students were most and least likely to use, and how these varied depending on whether students worked with a partner or alone. The findings contribute to efforts to assess what novice programmers learn by creating games.