Unlike a traditional game, you do not "play" errfix. Instead, you run it once to allow it to modify or verify the necessary system folders within your emulator.

ErrFix 3DSX is a homebrew tool designed for the Nintendo 3DS family of consoles. The tool is specifically created to fix various errors that users may encounter on their devices, such as error codes, freezing, or crashing. ErrFix 3DSX is not an official Nintendo tool, but rather a third-party creation developed by enthusiasts to help users troubleshoot and resolve common issues.

The app generates a single file on the root of the card: /fix_log_⎛⎝_˙ ͜ʖ˙_⎠⎞.txt Inside:

— a found recovery log, unnamed hardware, circa unknown