I just bought a Mid 9“ android tablet and need help.

I downloaded a paid game (Black Op Zombies) on my Android tablet, and the game kept on crashing. It turns out that the game is not compatible with rooted devices, which I believe this new tablet is (rooted). How can I find out if this tablet is rooted or not? Can this tablet be un-rooted? Is it worth unrooting? I'm asking because I really want to play this game, but I don't even understand the concept or meaning of the term “rooted android device“. Can someone please help me understand what is going on, and what I can do to make my tablet compatible with this game. Good thing is I already got a refund on the game, so I guess you can say no harm no foul if I can't figure this out. But if I can resolve this issue then I am interested in downloading the game once again. Any help would be greatly appriciated.

We'll my tablet is brand new with default settings. I believe it comes rooted from manufacturer. But my question is, is there any way to make my rooted tablet work with an app game that is not supported on rooted devices?