I'm surprised nobody has responded to this thread yet. I'm Technically not a professional game artist (or professional at all) but many of my friends and acquaintances are.
I'm not sure how much expertise you have outside of sculpting, but If you're a sculptor, a very important part of modeling for games you've got covered already. What you need to learn kind of depends on your goals. Rigging is a useful subject to know, but in a studio environment you won't need to be an expert at it unless you're a rigger. The most important subjects in a studio environment are understanding pipelines and ideally understanding high to low poly (or low to high poly if you work that way) workflows, as well as texture baking, both of which are essential especially for hero props, environment art and characters.
If I were you, I'd start by picking up a modeling kit. Preferably Maya and Max as these are industry standards (although you can get away with anything else) and just start modeling stuff. Look up tutorials, experiment a bit before exploring high to low poly workflows. Best way to learn is just by doing it. Get into modeling, UV mapping, some basic texturing, etc.
Again, it just really depends on what specific goals you have in mind, but generally a good place to start is by just exploring a 3D modeling kit, understanding UV mapping and high to low poly texture baking.
