How hard is it to study video game designing and CIA.

Pursuing a position with the CIA is a full-time role. It leaves no room for extracurricular activities. There are many types of roles at the CIA (e.g., a wide range of analysts). The requirements are extensive including excellent communications skills, excellent academic record, and many other skills. In most cases, joining the CIA also means graduating from an Ivy League school. The difficulty of joining the CIA should not be underestimated - it requires complete dedication and is not a guaranteed position for anyone. As a result, aspiring to create video games on the side is a somewhat unlikely goal. It's unlikely one would be able to complete their goals at the CIA while developing games on the side.

Side note: Working at the CIA is not like being in a James Bond movie.

On the positive side you can build video games on the side. Most game developers work on side projects all the time. We regularly encourage game design students to always be building a game for yourself.

The time it takes to make a game is variable you can do some simple games in engines like Unity or systems like Game Salad without a lot of help and there is a strong recreational (hobbyist) game community in most major cities and online.

The biggest concern I would have is what sorts of activities would the CIA allow and maintaining a separate computer for game design.

If the CIA doesn't work out the world can use great games.