Illustrator or Video Game Designer?

I don't see why one precludes the other. There was an RPG which cane out in about 2000, entitled "Dungeon Siege." It enjoyed a modest success, and an expansion was published. As RPGs go, it wasn't particularly original or imaginative, but it was backed up by Microsoft as an MMORPG.

I've got that game, played, beat it, never went online to play it, and lost interest in it. However, a few years back, i stumbled across a mod for the game. You could call it the "elf girl mod." Normally, you would select a human male or human female character. This adds the option to select an elf female character. She can move faster than humans and is more aggressive. She has a slightly improved magic resistance, acquires agility and intelligence faster than humans, but acquires strength more slowly than humans--the play balance is not upset by these characteristics. There are other details that i won't go into now, including one aspect which would greatly upset the play balance (make it too easy), but you don't have to load that if you don't want to.

But here's the thing about your question which made me think of this. When the elf girl puts on armor or a mage robe, you get a completely different appearance than you do with human characters. It is obvious that the woman who designed the mod is into fashion design art. There are even mage robes which are actually elaborate dresses that look like ball gowns.

So the woman who wrote this mod is a very skillful code write--the addition of the mod fits seamlessly into the game. She is also a good fashion design artist. There is no reason that you cannot pursue both goals.

Have you ever looked through the credits of a video game? There are thousands of people who work on each one.

I don't know for sure but I imagine they often start out with a script, then someone designs the characters, then someone creates a storyboard, then someone starts generating these ideas on a computer.

Look through the credits, look up what each of those jobs entail, see where your skills might fit in.