Cave Story, is slated to hit the 3DS eShop "in a month or so," developer and Nicalis CEO Tyrone Rodriguez told Destructoid. Cave Story+ is a remade, separate game from DSiWare's Cave Story 3D, not an update, meaning even those who own Cave Story 3D will have to purchase Cave Story+ new.
"I fought really hard to try to get it to be just a 'simple' update; I feel that Nintendo wanted the same thing too, but the logistics behind it are pretty huge," Rodriguez said. "The good thing is that if you already bought the DSiWare version on your 3DS and ever delete it, you'll still be able to download it. The update won't stop you from playing the prior version of the game."
A version of Cave Story+ launched on Steam last year, but the 3DS version will be different even from that iteration, Rodriguez said. The eShop version can't handle the Steam HD art or new music, but the sprites will be rendered in 3D, set to the beat of the original soundtrack.
Rodriguez teased a Steam update for Cave Story+ as well, saying, "You already know about the Cave Story+ Steam updates we have planned? How do online leaderboards for the challenges sound?" Sounds great, Rodriguez. Just great.