What exactly does a video game developer do?

He makes games, Duh.

X4J

rofl funny that

Developer is a (deliberately) vague term, referring to making games. Generally applied to companies rather than people. A developer designs a game, programs it, makes the artwork, writes the music, records the sounds, integrates the lot, and then sends it off to a publisher. Since a single person could theoretically do all that, a single person could be called a developer also.