可以详细解释一下句子中in which的作用，为什么用in which，这是个什么从句吗？

Question

‘Hide-and-seek’ is a popular children's game in which a group of children hide in secret places and then another person has to go to look for them.

Answer 1

我觉得这里应该用 that 一个同位语从句 in which引导定语从句，在从句中不作地点状语，而是作方式状语时，用in which；引导定语从句，介词in与从句中某些词语构成固定搭配，用in which。引导定语从句，但在定语从句中不作地点状语，而是作方式状语时，只用in which，不用where。

（1）This is the best way in which we can do the work well.

这是我们把工作做好的最好办法。

2.引导定语从句，介词in与定语从句中某些词语构成固定搭配时，只用in which不用where。

（1）He left his work in which he had been very successful.

他离开了他非常成功的工作。

Answer 2

in which 后面引导的是对game的修饰
译文：抓迷藏是一个孩子们中流行的游戏，一群孩子躲在一个秘密的地方，而另一个人去找到他们。

Answer 3

这是一个定语从句：in which=in the game.

Answer 4

这一个定义从句。
介词in加关系词which。