I have a design doc I can share, either contact me here, at levgree@yahoo.com, or on Discord (tag is levgre#1415). I am only going over some of mechanics in this post, with more focus on combat than campaign, as combat is the core of the game.  designers could possibly be welcome, at the least I don't ever mind getting additional ideas/feedback.

Like said in the title, the game is inspired by Darkest Dungeon, but aspiring for deeper and more varied combat/campaign mechanics.

Theme: the player controls a party of raiders that go on missions, getting loot, building up reputation and experience, etc.  These missions would often be populated areas like towns and forts, but also could be caves, forests, and other settings.  

The player will control a party of 6 characters.  Changing group formation and individual character positions will be an essential part of strategy for all party compositions.   However, most characters will still be in melee combat, as often the party will be fighting off enemies from both sides (just less often from the rear).

Characters, both friendly and enemy, will be able to die or be severely injured in one hit, and no magical healing available.  However they will be able to dodge or deflect most attacks until they run out of "stamina", at which point they become sluggish and easier to kill.  So gameplay wise, stamina behaves sort of like the regenerating shield in halo.  However if the player makes a tactical error or puts a character in a situation where they are outmatched, characters could still be wounded even at full stamina.  So individual battles are not the only threat, but also tiring  from waves of enemies.

 The player's group can rest when needed, but that will allow the enemies to ready their defenses or get reinforcements.  So speed and smart stamina management is encouraged.  Although, there will be some level of variety in approach, the player could have a more heavily armored team that slogs through tougher fights, or a lightly armored quick characters for a fast team that relies more on the element of surprise. 

Weapon and armor choices for each character will be significant strategic decisions, based on battle formation and also the strengths and weaknesses of the party comp/individual characters.

The exact setting is not yet decided, it could be realistic medieval, high fantasy medieval with demihumans and magical creatures and some level of magic, steampunk, etc..  The "raiders" could be seafaring viking types, fighting in a religious conflict like crusaders, or some of both.

Thanks for reading, and lmk if you are interested or have any questions.