>>11280347
List of games; https://f95zone.to/threads/unofficial-teratophilia-games-thread.250692/
Some relevant pixiv tags; 人外娘 (inhuman girl) ホラー (horror) 雌クリーチャー (female creature) 異形 (atypical appearance) モンスター娘 (monster girl) シーエ (Calcium, creepy Miku)
Try tag combinations, filter to R18 and make sure to add 00 or 000 if there's too many results

picrel is Terraria fanart, the artist has done monstergirl versions of most of the enemies, most don't suit this thread though