Machine Cave is quite the impressive work of art! Did you do all of this yourself? How long did it take?
Yeees... It took me about 3-4 months to make everything. I had to learn a lot of new things from tutorials and nesdev wiki online. I wanted to make more content but writing the game in C limited me to using small cartridge types. I'm quite proud of how well I optimized and structured the program code. Some of the program code is 3rd party, such as the audio engine.