The startled
feeling you have when
you realize, too late, something you should/could have done
differently, and usually blurt out,"Aw, shit, I could have {insert missed action here}";often occurs while gaming.
We were playing Munchkin
last night and I had a shitpiphany when I
remembered, too late, that as a Ranger I could have made
the cyclops into a steed instead of fighting it.