Here's a soundfont of the bass instrument used in many Sunsoft NES games, such as Mr. Gimmick, Gremlins 2, and Journey To Silius. There are two versions of the same instrument, one with pitch distortion (to stay true to the way samples were pitched on the NES) and one without (which is called 'PC' in the soundfont). The samples used come directly from FamiTracker, so they're pretty high quality.
Feel free to use this soundfont and its samples in any kind of project (Remix, Original Music, Video Game).