Many thanks to several people in the Apple II Slack who figured out how to verify this cassette digitization and convert it to a more usable format. I have no experience working with computer cassettes. Despite the fact that the Apple II predates floppy drives, emulator support for cassettes is spotty. @txgx42 was the first to confirm that the .cass file could be loaded in the Virtual II emulator by setting the cassette volume to 90. Analog hardware was finicky!

@txgx42 reverse engineered how the tape works. "The 30.300R overwrites the load end address (3E/3F), changing the 0300 to 07FF. It also changes the COUT hook (36/37) to $02B4, and fills the text page with the lo-res graphics data. When the load finishes, it returns to the monitor which calls COUT and so jumps to $02B4...

"...There it switches the machine into lores/text mixed mode and sets up to load the second file from the tape which contains the main BASIC code. After loading that it does its scrolling text thing and waits for a key press. then jumps into BASIC, which starts the program via a "GOTO 1" command that was left in the input buffer at 0200 by the first stage."

"...Also included in the box was a custom input device that consisted of 4 push-buttons connected to the Apple II's gameport. This allowed the 4 players to compete in real-time auctions for stock in companies which the players managed via those same buttons. It was a great challenge to work out how to input data with nothing but a push button but it taught me that interface is less important than play value and that auctions are a compelling way to interact."

Here's a video showing the (emulated) original cassette loading process in real time, then some gameplay: https://www.youtube.com/watch?v=9R7hfSILhsw