“show them Notch's time-lapse in the background on projector”
Time-lapse of making a game demystifies the creative process
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First, congratulations! I would demystify the process of creation. Show them your wireframes, your pencil sketches, talk about the business v. creative push and pull. Make it interactive - break them into groups of 2-3 each for 5 min and show them Notch's time-lapse in the background on projector while you have them work on exercises in ideation - what would their game be? what would the levels, characters, and challenges be. They don't have to present - just get them comfortable with the first step of creation - putting it on 'scratch' paper. If you have time, deconstruct Flappy Bird. The scrolling left to right background v. making the bird move. How the object detection is greatly simplified when you have only one coordinate to detect (y-bird and y-pipeTop/y-pipeBottom). How adding gravity to the bird (downward velocity) allows you to fly the bird. "Making Metagun" by Notch link "Creating Prelude of the Chambered" by Notch this video