If he knows what is going to happen then it is set in stone and you can do nothing to change it. He also knew that eve would eat that apple and made sure we would live and suffer. Maybe he just thought it would be more fun to watch.
I believe that although God knows who will go to Heaven or Hell, He leaves the decision for each person to decide. For instance, when babies first start learning how to walk, they are going to fall a few times. You may not push them so that they fall or hope that they do, you just know that it will happen. You also know that given the choice, your toddler might pick a cookie over asparagus. You didn't make them choose the cookie and may even be proud if they don't, but you understand why they made that choice. God is the same way.
However, a question rises that if he knows who is gonna go to heaven and who is gonna go to hell, why are we given chance to get a test!!!
As himself in holly Quran says " We created the life and the death of this world to put you human beings in the test, so that it becomes known which of you do nice works and which of you commit bad works."
I know from the title it sounds funny, but I believe that God knows the future, however, he knows all the futures. Our futures are branching. If we do this, go to branch A, if we do that, go to branch B. That is how I reconcile anti-predestination and omniscience.