I like this concept and the balls moving was responsive. No progression or sounds. My balls also started moving on their own.

I loved the concept of the game! During class you mentioned you had trouble getting the balls to roll up square hills. Here's how I would solve this: I would recommend overriding OnCollisionEnter/OnCollisionStay for that, then you can find the collision point with the steepest normal vector (where the y component is the smallest). If it's steep enough, after that you can translate that into a sort of "steepness" using a (1 - y) or (1/y) depending on how much you want, then use the dot product of the normal vector with the impulse along with some constant you tweak to apply an upward force. This would effectively cause an upward force to happen when the ball pushed against a wall allowing you to climb up.

I've just started delving into fire emblem games and this an almost exact copy of how movement works. Great job building this from scratch without any libraries added on.