Stratosfear is a (Mic) minigame in Mario Party 7. In this mingame, three players must try to dodge the Bullet Bills coming at them from the left and right while the other player holds the Microphone and controls whether it goes up or down in attempt to make the other players get hit by the Bullet Bills. In order for the player with the Microphone to win, all of the other players must have been hit by a Bullet Bill (which results in elimination from the minigame) before the timer runs out. If there is still at least one player still standing in the team of three after the timer runs out, then he/she and the rest of the team will win the minigame.
For player holding the Microphone: To move the platform up, say "Move Up" and to move it down, say "Move Down".
For the team of three: Use the Control Stick (a.k.a. Right Thumb Stick) to move your character and the A button to jump.