My edition of the play has an exclamation mark here.
There are relatively few exclamation marks in the texts. They seem
Bossy sometimes. Like they’re ordering an actor what to do or feel.
This one here, though, makes me laugh –
It makes me read Marcellus’ response to Hamlet as surprise – like
He’s startled him somehow and he’s thrown his hands to his face
In shock and saying “Good god!”
It implies, for me a sort of over-enthusiasm
For Marcellus to Hamlet.
This is punctuation, however (and it is an editor’s choice) – for this
I’d need to get all text geeky and look at a folio and both quartos
To even begin to guess if Shakespeare himself put that exclamation there.
Many a scholar will tell you to ignore all punctuation and I mostly do (even in my own writing – punctua – wha?) But this is one captivating exclamation work because it seems to say something
The words alone
Wouldn’t.