Boot Hill Blaster began as a submission for a NES-themed game jam where games had to use palette, resolution, sounds, and music available on the original Nintendo Entertainment System. The demo represents the state of the game as it was submitted and can be found on its game page on this site and on itch.io.
A full version of the game is still in development and will feature at least one more monster type and a soundtrack. You can listen to the soundtrack right now on SoundCloud. The songs and sound effects were created using FamiTracker. The game itself was written from the ground up and uses all original graphics.