#1: Usability: We need animations but we don't need the bells and whistles just yet. Just enough to create frames, animation speed, and something to set hot spots/image points. A full-bodied image editor can be created latter.
#2: Play Time: ONE flexible behavior such as custom movement, 8 way, or platform, as they tend to be the most popular and robust. One is just enough for people to start getting their hands dirty!
#3,4,5...: Functional tools: Global Variables, global objects, event groups, Intellisense/autocomplete for expressions...