Is it a platformer game? Is it a test ROM? Is it a repo I'll just delete before accomplishing anything because of all the sprite animation work it entails?
The Game Boy version has at least 30 coins. There is also an interactive exerciser used for hardware and emulator behavior testing. Building them requires RGBDS 0.6.1 or later, Python 3, and Pillow (Python Imaging Library).
The NES version has at least 12 coins. Building it requires cc65, Python 3, and Pillow (Python Imaging Library).