After several iterations of testing and repairing problems, the game is done. The game is very stable, and I haven't seen the game crash or otherwise go off the rails. The game is challenging, but I've played it the whole way through. I may post videos showing a "walkthrough."
I've shipped about half the cartridges. If you haven't received a shipping notice, your game should ship soon.
If you receive a damaged package or the game otherwise does not work, please contact me. I tested every cartridge just before shipping. I shipped the games in perfect condition, but sometimes packages get mysteriously damaged while in the hands of a postal service.
I tested the game mainly on my original front-loading NES. It should also work on the Retron systems, which worked for me. We all know the problems of a blinky NES. If your cartridge does not seem to work, try re-inserting it or try a soft reset. Your pin connector may also be loose (I'm on my ~6th pin connector).
I plan to share the digital files (ROM and manual) soon. I'll post a link.