I'll start by copying the comment I left on the Reddit post where I originally shared this project and then go into some more detail for this audience. (https://www.reddit.com/r/nes/comments/1umrnd5/i_made_an_inte...)

""" Castlevania II has always held a special place in my heart. I didn’t own it myself as a kid but I had a family member who did. This meant that I only got a few chances to actually play it, but that left a big impression on me anyway. I recently beat it for the first time and along the way I decided I wanted to build the most over-the-top guide you could imagine as an ode to the game. This is that guide. I hope you all enjoy.

Source code: https://github.com/baclap/the-ultimate-simons-quest-guide """

This is a Progressive Web App with full offline support. There are no static images or audio files used to create the guide. What it's actually doing is taking real binary data extracted from the ROM at build time, processing it at runtime in WebAssembly, and then rendering it using WebGL2. Similarly the game music is played from ROM-derived data through a Web Audio AudioWorklet that recreates the NES audio channels. There are additional curated JSON files that describe how all this data fits together on the map, the text from NPCs, the secret information, and so on.

This was really just a labor of love and something I'm proud to share. Looking forward to your feedback. Thanks for taking a look!