So I picked up a proto PCB for the SNES, and this is what was on it. A 1996 Tokyo Toy Show custom version of Super Nazo Puyo 2 (Which is a puzzle version of Puyo Puyo 2) for Super Famicom. Here's the first few images it presents, the title page and game screen are the same as the retail version, but these other screens are new. It's smaller than the released version, with only 2 4Mbit EPROMs onboard, where the release has 3 (8Mb vs 12Mb).

Click any image for larger version

This title page is the same as the retail version.

"For '96 Tokyo Toy Show"

Genre: Puzzle. System: Super Famicom. Media: ROM Cartridge, 12Mb + Battery Backup. Release: 06/28/96. Price: Y6800

Talks about a prize of a special telephone card for 3500 lucky winners who enter at the toyshow.