Have you tried Ghost of a Tale? I've only played it very briefly but it seems pretty decent. The description has it mislabeled as an action-RPG, but it's a pure stealth game.
https://store.steampowered.com/app/417290/Ghost_of_a_Tale/
Stealth games shouldn't have combat options at all. Look at Styx, or Aragami, or Dark 2013, or Ghost of a Tale. None have an attack button.
Haven't played any of these but they look interesting, thanks.
Hang on, though:
Stealth games shouldn't have combat options at all.
That would take Thief out, since levels like Return to the Cathedral and Strange Bedfellows nudge the player towards using combat against the creatures that have overrun the cathedral and the Hammerite temple.
You can but it's not easy. Good luck playing like that on Expert SCCT. Or Hitman on highest difficulty.
Not sure about this - in Hitman it was always easier to cause a massacre than it was to play the game properly, which is why the game has the ranking system to try and dissuade you (just like Dishonored). I remember playing Hitman 2 as a kid and getting so pissed off with the disguise mechanics that I just drew the silverballers and cleaned the level out to get to the next map. The new Hitman games even have cover shooting to make the maximum violence approach even easier.
I accept the definition of stealth game that you and JDR13 put forward but it still feels strange to me - it'd mean that Thief ceased to be a stealth game if everything about it was the same, but the sword and archery mechanics were improved. Like, Deux Ex HR clearly
wants you to remain undetected in the same way Hitman games do, even if you ultimately decide to reject the core game mechanics and go on a shooting spree instead. The levels are filled with alarms, guards have states of awareness, there's air vents every 3 steps which allow you to bypass enemies, there's heavily signposted stealth routes through each map, etc.
The original Deus Ex I can kind of see being argued to be more of a stealth-FPS hybrid because ghosting places like Ocean Lab and Versalife requires you to start doing some fairly ridiculous shit and the game seems to want you to start shooting somewhere around the time you reach the Chinese ship, if not earlier, but HR is made with stealth in mind the whole way through.