Your adventure begins in the first world called "A". You are given a device called Jammer, which allows you to open doors and stop different objects.
Take the Jammer by clicking the interaction button and set it in front of the first door, it is the basic action in this game.
Go further, in every level you will be given a new device. You don't need to take the jammer to the next puzzle. Take the next Jammer and use it on the metal ball.
Take another jammer and use it on the same metal ball. Move the first jammer so the ball will remain immobilized and you will have one free device in your hands.
Set the free jammer on the sentry gun and you can safely get to the main part of this location. From now on, you can solve the riddles in any order you want.