Demakes (What game would you wanna send back in time?)

[Koh]

While not really a demake, there was a decent unlicensed metroidvania Castlevania on GBC, called Castlevania DX. I ran through it a year or so ago here: https://www.youtube.com/watch?v=H9oUrGRF...tBrEa-uY75

If it had more polish, I'd say it could easily work out well in that regard.