For this challenge in particular, you’ll want two things, both installable through Homebrew. From a terminal, type:
brew install nasm qemu
This will give you both nasm (the assembler) and QEMU (a reasonable PC emulator). There are other options for both, but that’s what I used when making Snakelight!
Other nice emulators you might like to test with are DOSBox (available from brew install dosbox) or 86Box.
programs that simulate a PC, so that you can test the game. writing to USB and actually booting an actual computer from it is possible, but it’s not as fast as just running it in a simulator
