According to the teachers, the game which challenges kids to use their imagination by building virtual worlds complete with anything they would like to see in their future ...

是的，句子不完整，只有主语，没有谓语，因为整个黑体部分是定语从句。

challenges kids to use their imagination：激发孩子们去运用想象力。

by building virtual worlds complete with anything they would like to see in their future：“通过构建......”，定语从句中的方式状语。

complete with anything they would like to see in their future：complete with 复合介词，“连同；包括”。

they would like to see in their future：anything 的定语从句。