You think about a Mix of Thief and dishonored, i guess? Least Puzzle, more Sandbox stealth but Open for the Player to approach the Situation (and Not so much Tool/scenario Drive Like the Hitman Games). I would add Safe zones/Houses as in Nobody finds you there. So you can avoid running away from every enemy on the Map, which offen Happens If you have to flee. This could add some kind of inbetween restock or Adaptation options etc. Think espionage Thrillers and so in.
The Expanse itches