Thank you for the kind words.
There are 8 audio tapes in the game, for reference. After the tape titled "Mixtape", you have to find the Basement Key to go into the basement. Its on the second floor on the table. We realized it was pretty hard to find when it was too late. The game is over when you get sent back to the title screen.
Hope that helps and I would love to hear what you think if you decide to go back and finish it :)
You're right, we should probably get a full playthrough video up.