So this is really cool! Modder Batandy has basically recreated the entirety of the first NES Castlevania game using the original Doom engine! And you can check out some of the gameplay at the top of the article!
Here's the official description:
Castlevania : Simon's Destiny is a standalone non-profit GZDOOM based fan game born as a love letter to this legendary franchise. This game aims to reinvent the very first NES title of the franchise with a nostalgic yet brand new first person gameplay.
All the levels from the classic NES era game have been reimagined like never before, experience the tale of Simon's fight against Dracula and his army of the night!
This game is completely standalone, only GZDOOM is required to play!
Now, to be fair, this was originally released in 2017, but Batandy has just released what is the last patch in the game to finally complete it! Meanwhile, you can download the full mod for yourself on Batandy's official itch.io page here!
But what do you guys think? And who do you think would win, Doomguy or Simon Belmont?