The Grand Compendium
Original Series Spreadsheets
The original Megami Tensei games (including their collective remake, Kyūyaku Megami Tensei), loosely based on a series of horror novels by Aya Nishitani. These games defined many of the basic gameplay conventions, such as demon negotiation and fusion, that would become trademarks of later MegaTen games. I've played all of the original series, but have not beaten the NES version of Megami Tensei II.