In the narrative, the Devil has corrupted the arcade machine, and you must use legitimate code snippets to patch the game, unlock shortcuts, and break demonic seals. The "Code Storage" is represented as a text box or a hexadecimal buffer that you can view between levels or when interacting with certain glitched terminals.
Mullins briefly updated the game with fresh codes, but the sheer volume of players meant they were often claimed within minutes. How to Find Secrets and "Code" in Pony Island pony island code storage