In fact, i do remember and i can sketch it out.
Exhibit A: Main combat scene looked something like that. Initially the protag was all alone, but quickly birthed her first daughter to fight along het in the tutorial. Turn UI and personal stats UI might be flipped places, i just remember two sets of colored lines both at the top and the bottom. Also obviously daughters and monsters had HP and Lust bars but i forgot to add them to the sketch.
To initialize breeding the lust meter must be full, typically that of a monster. If heroine's lust is full she can't do anything except breeding and taking hits iirc.
Exhibit B: Map. Map consisted of several biomes you can travel between, looking for encounters. I don't remember if you traveled as a PNG or just clicked on encounter nodes to proceed further. Probably as a PNG, now that i think about it, i remember running around in cave biome from little pebble dudes and some gray-skinned goblinoids, just exploring. I distinctly remember getting stuck at cave biome, either because i got bored, had to go out, because it was too difficult or because it was unfinished yet.
Exhibit C: Base. At your base of operations you could spar (i don't remember if girls sparred between themselves or with the monsters, but it allegedly did grant EXP), sleep (i think it was animations replay?), have some conversations (i'm pretty sure the witch that initially tutored you on breeding was there) and review breeding strategies (it had several). Monster cage for breeding might be me misremembering something else that was there, like and NPC or a building.
Finally, Exhibit D: Breeding Strategies Manual. It showcased how to obtain initial hybrids by breeding the protag and monsters, and which combination of crossbreeds you can acquire by further breeding your daughters with various monsters. Of course those you didn't encounter yet were grayed out, exploring and figuring stuff out was part of the fun and appeal. And i'm pretty sure some girls were breedable with each other (circle+circle)? Maybe through sparring? It was a very long time ago, i just remember that this screen existed. I remember opening around half of it before stopping.
That's about it. Salamander Girl and Harpy Girl from the thumbnail of Monster Girl Hunt remind me of this unknown game's art the most. I think it had some extremely similar designs. Or i'm tripping, which is also a possibility.