Homebrew developer Jweii, who is known for making demakes of modern games, has released a gameplay video demo of an NES demake of Castlevania Symphony of the Night that they made.
The demo was made in 26.35 hours in the span of 9 days.
Jweii has also made an Atari 2600 style demake of the original Castlevania
See the demo below
https://www.youtube.com/watch?v=fCmYW4M1A40&t=60s