Do Universalists believe God just put us on earth to be puppets?

I certainly don’t believe God put us here to be puppets. And I don’t know a single Christian Universalist who thinks God did.

If God hasn’t given us free will to decide on accepting Him for salvation, aren’t we on earth to be nothing more than puppets?

Christian Universalism in no way denies free will. Everyone has the ability to accept or reject God’s call. The Christian Universalist simply asserts that, in the end, all will freely choose God. And they find many passages in the Bible to support this.

I suspect you are making the faulty assumption that if everyone makes the same choice, then the choice wasn’t free. This is clearly false. We all choose to eat, drink, and breathe, yet no one denies free will based on that. 

To this you might respond, “But eventually hunger will force a person to eat and thirst will force a person to drink. Under those circumstances it is not a free choice. Likewise, those brought to a point where they must choose God did not make a free choice. They were compelled to choose God.”

If this is your definition of freedom -- the ability to choose contrary to one’s nature without consequence for all time -- then I’m afraid no one has free will. We all operate within the confines of human nature, and built into human nature is the need to commune with and love God. 

We can turn away from God, but we will always need Him. We cannot shed that need like a snake sheds its skin. It will always drive us back to Him like hunger and thirst drives us to food and water. So in that sense we are not free, no one is exempt from this compulsion. It is built into us. The more we turn away from God, the more pain we feel. Choosing God when in pain is no less free than choosing food when we are hungry.

If that’s true from a Universalist’s point of view, is God making some humans do horrible things on earth?

Again, Christian Universalism doesn’t deny free will. It only denies that anyone will use their free will to reject God for forever. God isn’t making anyone do anything horrible. We do it to ourselves when we use our free will to turn away from God. So, no, we are not puppets -- far from it.