Default controls are WASD/arrow keys; can be configured in the options menu "It's basically like DDR, press arrow when arrow over other arrow. And uhhh don't die." MODDING: https://cabalex.github.io/fnf-song-converter/guide/
Huge thanks to @cabalex for the engine and the tutorial! Without it, I never could have made this! In the comments, please show words of support.