How do people design video games?
It usually takes a long time. Years. They need to come up with a story, then story boards, graphics design, hire actors for voice parts, create score, etc. There is much work that goes into most video games.
A lot of computer work
It consists of a lot of computer codes. The game has to be tested multiple times as well. Video game developers do a lot of work
If you want to make one try a program called unity. Helped me make and license mine