Best throwback RPGs on Steam?

Divinity Original Sin

Septerra Core!
EDIT: Not sure if it applies to anything you typed aside from being RPG

You might want to check out Spiderweb games. (Avernum, Geneforge, etc)

Eschalon Book

New games with an old game feel? Divinity already mentioned, start there. Wishlist Wasteland 2 while you're at it. Can't think of anything else atm.

Edit: Oh, Aarklash Legacy, which is on sale right now. That's more strategy than RPG, I've heard.

Divinity Original Sin is both new, shiny, and styled like an old-school RPG. I highly recommend it.

Spiderweb games is pretty solid. I loved Avernum Escape From the Pit, more than I have Baldur's Gate (so far, haven't played BG as much). One catch though, it's a remake of the original, so it's old style but newer? Still has graphics that make you think you're playing in the 90s though, it's just that the UI and what not is really cleaned up and better controls, can't really go wrong IMO

Try the Shadowrun remake.

Wait for Pillars of Eternity

People named pretty much everything I can think of. Does Jagged Alliance count?

Star Wars: Knights of the Old Republic, and Witcher are excellent RPGs on Steam. Planescape: Torment, and Anachronox are not on Steam, but they are also incredibly good.

Gothic I, II Spellforce