To unlock Cassette Cars, you must first complete the game on any difficulty. Once you have done this, you can access the Cassette Cars codes by going to the main menu and selecting "Extras". You will then see a list of all the available codes. To use a code, simply enter it into the text box and press "Enter". The code will then be activated.
Be sure to note that some codes may only be available after completing certain challenges, such as beating a certain boss without taking damage.
