Getting into game design involves putting in a lot of work in many areas. Building the game design concept passes through steps, that may get rougher then you think. If we are talking gameplay it's not merely enough to just think up the rules and throw them in. As with just about everything - rules can and will be bent and those are the cases that make things hard yet interesting. How are you enforcing your rules ? Do you encourage rule bending and to what extent ? If you do, at what point do you stop, because if you don't, your game is totally going to break. Looking into a game design draft is a process that has to undergo massive critique - at first it will have tons and tons of loopholes in logic that will need fixing. After that you'll have many other such things to worry about. Keep in mind that this is just one side of the cube. There are tons of other aspects to think about.
Those and many other reasons are why I would recommend that you start off by actually building some games, instead of thinking how to enter the industry head first. And I'm not talking about video games either - try something more old school. Build a board game, a card game or something that you can produce and get a playable version faster. Then give it to a group of people to play. Then watch and learn. They will probably demolish your initial design, you'll fix, they'll demolish again and this process is going to go through until you finish your idea in a way that is playable, enjoyable and acceptable.
If after that you still want to be a game designer, start by building smaller games - the mobile market is pretty open to those kind of ideas. Build a portfolio with your designs. Try to gradually upgrade your design skills to a point where you feel that your product is good enough for you to start looking at a job in a studio.