What is the mood at the opening of "Hamlet"?
The mood at the opening of Hamlet is one of suspicion set in place by the motif of watching. The Sentinels wait for the Ghost of King Hamlet to reappear and their worst suspicions will be realized - that foul play is indeed afoot. Shakespeare uses the opening scene to underscore the continuing suspicions of young Hamlet concerning his father's murder intertwined with the motif that nothing or no one will be able to go 'unwatched' in Hamlet's "prison-house" world. Hamlet watches Claudius and Gertrude, and Polonious has spies upon his son and is murdered watching Gertrude and Hamlet. Hamlet employs players to watch Claudius watching a play to uncover his guilt, and all seems to be put into motion because of the Ghost in the opening scene.
In one word? Tense.
In a few more words? Scared out of their minds. These are experienced guards who have seen battle. They know what to do with physical danger. However, a ghost has been appearing. This period was much more intensely Christian than modern times, and believed more intensely in ghosts and the supernatural in general. A ghost was both a serious threat and a sign that something was wrong.
Tensed atmosphere which sets the mood for the play as a whole. The fact that 12 had just struck may indicate the element of supernatural. Besides the questions asked in the first scene foreshadows the same questions which Hamlet would be asking throughout the play. Also introduces the theme of uncertainty
The mood at the beginning of Hamlet is one of mystery. There is also an atmosphere of evil and darkness because the play opens with the 12 o'clock hour being struck by the clock.
It was very scary and frightening as the guards who are experience in war and danger had seen an ghost apparition and dark forces appearing in the castle.
Ghost had long believed to be the agents of the afterlife and could have represented the Devil, which instill fear into people.
The dead king's armor on the Ghosts tells us that a soldier could have rise up from the dead to complete a task that wasn't finished or an omen for a country to await their doom.