One rule about past perfect that I've been taught is that
If the sequence is clear, the usage of past perfect or simple past is optional.
For example, I had eaten the cookies, and then I went to bed to sleep.
The sequence is clear (marked by then).
But, I'm not quite sure about after and before. Examples:
- I had stopped playing game before my mother came.
- I stopped playing game before my mother came.
Are they both grammatical because the adverbial (before my mother came) shows the sequence?
And for after:
- After I had played the game, my mother came.
- After I played the game, my mother came.
I just want it to be clear, can "Before" and "after" allow or forbid the usage of the past perfect?