I don't know if that's a game stone or not. But, and I'm not trying to be funny or cute, you really got that sucker to spin! Also, I would not despair or be upset if others don't see what you see. I don't know what region you live in, but if you want to find artifacts, you will find them by learning about artifacts from your region, and putting the time in.
As far as this specific rock, I don't know what kind of surface a prehistoric native would use, or why. Again, not trying to deflate you, or discourage you. But that was a hell of a good spin.