Press the q key to activate the jet pack. See if you can add keys to move the jet man to the left and right! As a challenge, this could be made into a game where the jet man has to dodge obstacles. Or maybe collect objects.
Third attempt to create a jetpack character who is pulled down as if by gravity but has a thrust to push him upwards. Problem: the thrust continues to build. Need a way to set it to zero when key released. Solved with an if statement. Didn't work at first because kept resetting to zero so thrust never got above 0.1. Stopped this by putting the not statement in so that if you hold the q key down then the thrust is not reset to zero. Added an increasing gravitational effect by making gravity(ie the negative change in y ) a variable. Tinkering with the changes to this alters the speed at which gravity increases.