There's a very simple and actually somewhat mundane idea for a game that's been on my mind. Simply put, the party is traveling to a place far away (with the appropriate amount of hurdles and forks on the road there) but towns are spread really really far apart. Highlighting the struggles of simply traveling. A Human vs Nature conflict. Hitting on things like preparation, surviving rough conditions, carrying survival gear vs valuable loot, and learning from previous mismanagement.
Turning choices that would otherwise not be a big deal into a tough call. "Do we drop our surplus food for this valuable barrel of oil?" "Do we travel over the mountain bearing the elements or travel through the mountain in the dwarven ruins?" "Do we hire a local guy who knows the route because this next stretch of road is more dangerous than the least, or do we buy that second mule we've been talking about?"
I'm looking for the right system, one that will work with me instead of against me. I know Ryuutama has a focus on a travel-based campaign however it's tone seems a bit too light, just need a little more edge. Maybe D&D Basic/Expert would work (starting at level 3ish) or maybe some retoclone like Lamentations. Burning Wheel isn't reliant on combat to maintain interest, so that's an option but doesn't have very strict rules on carrying things so I'd have to find/make some. I don't know how well Torchbearer handles overland travel. It has an inventory system that's a bit too specific, a level of detail I'm not interested in. Torchbearer is also a bit too severe in tone.