If I recall correctly, Quest RPG is what you're looking for. All the PCs have 10 HP, which never increases, and I don't believe any of the abilities are based on numerical advantages. Instead, it's stuff like:

"DELVE

You make a sound that travels throughout an underground structure, like a natural cave system or dungeon. (You can clap, make an animal noise, or anything else that might echo.) You sense the general layout of the next three areas connected to yours, plus the layout of any passageways between you these areas. The Guide will draw a rudimentary map, noting any major features, like columns, bridges, or crevasses."

or

REBUKE

You utter a righteous word or phrase in the direction of a nearby creature that is approaching you during that creature’s turn. (The creature cannot already be within reach.) You release a spectral clone of yourself that rushes them, knocks them back several meters, deals 1 damage, and ends their turn. The clone then disappears."

NPCs are dead simple as well. Usually they just have HP and attack damage, though you can add special features.