Oh also some concept for how a hypothetical game would work.

You play as three different humans on an expedition into MT. Ebbot (unrelated to the MT. EBBOT Mining Operation)

healing is very limited, like at very most 1/4 of Undertale’s items are available. Your primary form of healing is resting, but this comes with risks.

1. Random monster attacks which may leave a party member unable to explore the following expedition

2. Contaminated water preventing a full heal and applying a weakness effect

3. Nothing. Everybody full recovers

4. Maybe some others if I or you guys think of something

Also a good route does not relate to you forming better relationships with the monsters, but among the humans you play as. Although sparing monsters can have its benefits