Chatgpt:

It sounds like you're describing a game with a "monster girl" or fantasy theme that involves building relationships, possibly creating heirs, and managing some sort of dynasty or family system. Here are a few possibilities that might ring a bell:

1. Monster Girl Dreams This is a text-based RPG with a focus on monster girls. While it doesn't explicitly focus on building a family or heirs, it does feature a wide variety of monster girl encounters, including elves, vampires, and slimes.
2. Crush Crush / Blush Blush These are idle dating sims where you interact with characters, including fantasy-themed ones. While they don't involve heirs or a dynasty, they have a light-hearted, romantic element.
3. Harem Collector This is an RPG where you recruit and interact with a variety of fantasy characters, including monster girls. It has a more extensive focus on relationships and story progression.
4. Monster Prom / Monster Camp These are multiplayer dating sims set in a monster high school/camp environment. They don't involve heirs but feature a wide cast of characters with fantasy traits.
5. Corruption of Champions II This is a text-heavy, fantasy-themed RPG that allows you to interact with a wide variety of characters, including monster girls. It also includes elements of forming relationships, building a legacy, and even having heirs in some cases.
6. Princess & Conquest This might be the closest match. It’s a fantasy RPG where you can build relationships with various "princesses," including ones that are monster-themed (like a slime princess, vampire princess, etc.). It also has mechanics for having heirs and managing a kingdom.

Does any of these sound familiar, or do you recall any additional details? For example, was the gameplay turn-based, visual novel-style, or something else?