If you have a decent gaming PC, you can now emulate the original Demon's Souls at 60FPS, which is great. The Demon's Souls Remake is really good too, but if you're primarily interested in looking at the progression of the art, that Remake took things in a somewhat different direction (as it was made by a different team). It's incredibly faithful gameplay wise, though.

Be sure to check out Bloodborne as well.