Jango40

This article by Liz England explains what her job as a Game Designer is and what other roles do in relation. Definitely worth a read and look at her other posts: http://www.lizengland.com/blog/2014/04/the-door-problem/

If you're going to create a game from scratch by yourself, you need to understand/learn basic physics kinematic theory (I don't even remember what it's called), Force = Mass × Acceleration stuff.

Nah, I don't think physics is entirely necessary. Depends on the game.