Pass the Ball: All players in a circle. Ask the players to pass a mimed ball [present] to others (one ball at a time). The ball becomes heavier, until it weighs a ton, or extremely light, extremely big (and light or heavy) or extremely small (and light or heavy). Actors need to show the ball's characteristics in the way it gets passed.
Mirror Exercise: Pair up actors. One actor is the mirror and must copy everything the other actor does.
Shrinking Box: Actors pantomine that they are in a very large box. Show audience all the sides. Then the box gets smaller. Show the audience how small it is getting. Then they must figure out a way to escape. The actor must do a good job showing the audience how they have escaped so they can correctly guess how.
Group Stop: Everyone quietly mills about the room. One person will elect to freeze in position unexpectedly. As soon as one notices that someone else has frozen in position they freeze as well. So the effect of one person freezing causes everyone to freeze. Once everyone is still the group starts milling around again. The goal is to see how quickly the group can freeze in position.
3 Noses: A fun and silly game. Let everyone walk leisurely around the room. When you shout '3 Noses' the players must form little groups, each group consisting of 3 touching noses. Use your imagination - say 4 feet, 3 hands, 2 ears, 9 fingers, 5 hips, 4 elbows, 3 heads, 7 left big toes, 4 little fingers. Repeat till everyone is giggling.
Alphabet Game: The actors act out a scene but they must start each sentence with the letters of the alphabet. If an actor gets a letter wrong, audience yells SLEEP and remaining actors continue.
Fairy Tale in a Minute: The actors pick a fairy tale (or get one from the audience) and then act out the story in one minute. Then they must act out the same thing in 30 seconds. THEN they must act it out in 10 seconds.
Lines from our Pockets: The audience will write lines for the actors to say. Someone will collect the lines and not show them to the actors. The actors will act out the scene and then they must interject the lines into the scene.
Melodrama: We have an old fashioned melodrama for you, but with a twist. The twists will be based on suggestions from the audience. We have three characters: a damsel in distress, a hero, and a villain. Audience: you will Boo at Villain, Cheer for Hero, Ahhh for Damsel. Audience will suggest... Damsel: something strange to raise on a farm, Villain: a weird form of torture, Hero: an odd weapon someone might use to stop a villain.
Stunt Doubles: 2 Actors are acting a scene such as washing a car. When it comes time to do a "dangerous" step (such as turning on the hose) they call in their stunt doubles.
Here Comes Jill: One actress plays Jill who is off stage. The other two actors are patrons at a restaurant and describe what Jill is like while she is off stage. Jill is a waitress and when Jill comes in, she has to act like she is described.
Flock of Seagulls: You have a lead actor and four other actors who must copy everything the lead actor does. The problem is that each of the other actors have some sort of problem. One has their foot stuck to the floor, one can't put their arms down, one has their hands stuck to their head, one keeps falling asleep (add your own problems).
Honey Walk: All actors walk in place. The audience calls out different things they must walk through. Snow, ice, mud, jello, honey...
Here are directions for complete improv workshop: http://www.freedrama.net/improv.htm
Fun fill in the blank improv plays called Mad-Scripts: http://www.freedrama.net/madscripts.html
Hamlet Improv Workshop/Show Ideas: http://www.freedrama.net/theme.html
Share your improv game ideas in the discussion below!