Sadly i dont know if this can be learned persay as it wobbles along the “creativity” line.

Id say that youd need to have a genuine curiosity along with a “what if” mindset that is hard to teach. The path to these ideas is often a train of what ifs, what if snake was 3d? Then what if it was 3d on a planet? What about a cube?

You can take the same thought to other games. What if pong was 3d or on a sphere? What if pong supported 100 people playing together? How would that work?

Often what ifs will be deadends or uninteresting. It is like sales, a volume game. But u got to like the process or you wont get far.