how do I become a video game designer

Learn programming to start with. Once you know programming, you will learn the concept of game design. The end result a video game is a combination of many different modules (graphics, background, music, movements, tools, etc.). You will need to learn about how each module works and work with teams who develop each module and combine them together. Of course imagination and creativity also plays big part in designing a game.

Investing more time on the design and the concepts of the game and then research to implement new ideas into the game and what kind of games people like more.