I've seen this misconception a couple of times now, but Shiro no Yakata and Shiratane Tower are NOT the same game. This game is Shiratane Tower, Zell's own game that's more aligned with his tastes, being more monstrous girls and heavy femdom. Shiro no Yakata is a game with a similar themes that was originally soley started by Zell before Shiratane, but he asked for help from Ansala, the dev behind Succubus Affection, leading to the content getting changed. The reason Zell decided to start making his own horror themed game was because getting Ansala on board for Shiro no Yakata meant foregoing monstrosity on the girls and more of a focus on maledom. Zell isn't bothered by a more vanilla game, but it certainly isn't his preference, which led to him making this game on the side. You can tell the games are different because Ansala very much likes maledom and this game has absolutely none of it, as well as Shiro having combat and attack spells while this game has purely defensive and tricky magic to avoid getting caught.