Ib is another game that doesn't have an anime to use as source material. But much like Yomawari, Ib boasts an aesthetic that will have special appeal to anime fans. In this RPG Maker horror game, a young girl gets trapped in an alternate world after going to an art gallery with her parents -- and now she has to find her way back.
This is a choice-driven game that will result in different endings based on the decisions that you make while you play. It was originally designed in Japanese, but a translated version is available at the link below.