What are five techniques Shakespeare uses to create suspense in Act 1 of Hamlet?

1. At the very beginning of the play, the men on guard seem nervous: "Who's there? / Nay, answer me: stand, and unfold yourself . . . Stand ho! Who's there?" They seem to be on edge, expecting an enemy or confrontation of some kind. It is also night time, meaning that potential enemies might be hiding close by. This creates suspense for the audience because we are left wondering what or who the men on guard seem to fear.

2. The appearance, for the third night in succession, of the ghost of the king ("the same figure, like the king that's dead") creates suspense because we, the audience, wonder how the king died and why the ghost might be wandering around the castle. Ghosts in many cultures are thought to return to the land of the living to settle unfinished business, or to redress some kind of injustice. Thus, the appearance of the ghost would also prompt an audience to wonder what that unfinished business or injustice might be.

3. When Hamlet is introduced in scene 2, he comes across as suicidal ("O, that . . . the Everlasting had not fix'd / His canon 'gainst self-slaughter") and angry ("Seems, madam! Nay it is: I know not seems"). This creates suspense, because the audience will want to discover the reasons behind these extreme feelings and will want to know what becomes of them.

4. When Hamlet speaks with the ghost of his father, in scene 5, we learn that Claudius, Hamlet's uncle, poisoned and murdered Hamlet's father, the old king. The murder was callous and cowardly ("Thus was I, sleeping") and was carried out before the king had had a chance to repent of his sins: "No reckoning made, but sent to my account / With all the imperfections on my head." The act of murder, and the way it was carried out, creates suspense because we wonder about the character of Claudius, the new king. The murder raises questions about the character of the new king, the motives behind the murder, and also about the fate of Hamlet's mother (the new king's new wife) and the kingdom.

5. During the same scene, the ghost instructs Hamlet to "Revenge his foul and most unnatural murder," and Hamlet in reply exclaims that he will, "with wings as swift . . . as the thoughts of love . . . sweep to (his) revenge." This creates suspense that endures for much of the play, as the audience wonders if and how Hamlet will succeed in exacting his revenge.

How are tension and suspense created in Act 1, Scene 1 of Hamlet?

When the scene opens, Barnardo is arriving to relieve Francisco from Francisco's shift on watch. Despite the fact that Barnardo knows Francisco is there, on guard, Barnardo is on edge enough to ask, "Who's there?" (1.1.1). He knows who is there: the person he has arrived to replace! This prompts Francisco to insist that Barnardo must "answer [him]," and he tells Barnardo to "Stand and unfold yourself" (1.1.2). However, Francisco observes that Barnardo is prompt, arriving exactly on time, saying, "You come most carefully upon your hour" (1.1.6). In other words, Francisco ought to have been expecting Barnardo's arrival as well, and so he ought not, perhaps, to have been so defensive when spoken to in the darkness. In short, both guards seem to be a bit edgy, and though each of them expects to see the other, both are nervous enough to demand identification when they do.

Likewise, though Barnardo and Francisco anticipate the arrival of Horatio and Marcellus, Francisco orders them to "Stand ho!" and identify themselves right away as well (1.1.15). Everyone, it seems, is feeling a little anxious. Given the fact that a ghost who looks like the dead king has been seen here, it is no small wonder.

Soon, Marcellus goes on to describe the strange goings-on in Denmark: they are required to guard the castle at night, new cannons are being made and other implements of war are readied, new ships are being built quickly (so quickly that the builders do not even get Sundays off), and so on (1.1.81-90). No one, apparently, knows why, and the speculation about imminent war builds tension as well.

Tension and suspense are created from the very beginning of the play.  The first act and scene features a midnight watch in the bitter cold.  They are joined by Horatio, a close friend of the title character Hamlet, and hope that he can help them sort out a strange, ghostly occurrence.  It seems that the ghost of the recently deceased King, Hamlet's father, has been appearing at night, dressed in his army as if ready for a fight.  This has frightened the watchmen and does thes same to Horatio, as noted by one of the guards, Bernardo:

How now, Horatio! you tremble and look pale:
Is not this something more than fantasy?

Beyond the appearance of the dead king, Horatio relates a bitter rivalry between their home, Denmark, and neighboring Norway.  With a dead king, an attack may be imminent.  In addition, Horatio compares this evening to the night of Julius Caesar's death when the dead rose from their graves and likens it to foreboding doom.

A little ere the mightiest Julius fell,
The graves stood tenantless and the sheeted dead
Did squeak and gibber in the Roman streets:
As stars with trains of fire and dews of blood,
Disasters in the sun;

All of these things raise the level of suspense and tension in the reader.