Simple design tips... What is "enough?"
1. A dungeon that is simple, proceeds in stages, and has a simple puzzle (and random encounters) can be effective.
2. Extremely simple spacial positioning.
Having two groups, enemies and player characters, standing in lines opposite each other, and taking turns inflicting attacks or casting spells, can be enough. This is especially effective as a default positioning for battles.
3. Spells can be extremely simple.
Knock, Fireball, and Speak With Dead are great.
4. Means of transportation tiers exploration.
It's a JRPG staple. Walk across the continent, then get a ship and go visit other continents and explore the sea. Maybe find portals between various places. Eventually you get an airship, which lets you visit floating islands or other planets or whatever.
It's a simple principle to apply. Less transportation, less settings. More transportation, more settings.
5. Arbitrary Monsters
Monsters can, and should, be whatever. Meaningless details or additions can be handwaved or explained. A monster is an open-ended template which players KNOW how to deal with.
5a. corollary: can NPCs be anything??
6. Chasing after a big bad vs. simulating colonialism.
Instead of raiding indigenous peoples, pursuing an antagonist around the globe allows the players to be problem-solving-tourists aka traveling heroes. They need not pursue, but then bad things will happen.
7. Nonspecific NPC Monotheism.
Having all or most of the NPCs worship a single, semi-mysterious deity has its advantages. There's a simple and uniting cultural touchstone everywhere the players look. The Goddess is good and the people who worship her (most people) are basically good. This contributes to Simple Ethics.
8. Simple ethics can be fine.
An overtly evil antagonist will likely speed gameplay along.
9. Cooperating with monsters is easy as shit
You probably already knew.
10. What if there are already lit torches underground?
If you don't want to track light, why not have torches line the way? No one's going to complain.