I thought of this on my own, and found "Magna Putt" while searching for prior art. Let me first say that this is not an idea to help you cheat your opponents on the course. It is an idea intended to make the game a bit more challenging than it already is, to add a new dimension of play for those who
they've already mastered the game of golf.
This game is played exactly the same way as traditional golf, but has has two components which differ from traditional golf: magnetized clubs, and a magnetized ball.
The ball is an ordinary-looking golf ball, but the core is a magnet. The idea is to try to accurately send the ball where you want it to go by manipulating the magnetic fields.
If you turn the ball one way, the core magnet will repel the magnetized head, making it difficult to strike the ball with the part of the head you want. If you turn it the other way, it will try to stick to the head, again fouling up your aim. If you turn it just right, the opposing poles might add a spin to it. The trick then is knowing the best direction to have the ball facing on the tee, and which part of the magnetized head to strike with, to make the best use of the magnetic fields.
The magnets don't have to be that powerful, either, since even a small nudge of the ball can have a drastic effect on the trajectory.
Every player would use compatible equipment, so there is no advantage for anyone (except, possibly, those with an understanding of magnetic fields).