Most Darkest Dungeon mods make the game easier... but not this one! Forget delving into the abyss with a group of four heroes to assist one another. That's all but a distant memory with the Lone Crusade mod, which has you play through the entire game with no one but the Crusader Reynauld.
Obviously tweaks are made to the enemies and bosses, since there are places where one character can't possibly win normally. But don't think this mod is doing you any favors. The difficulty is ramped up even further than normal -- and if Reynauld dies, you get to start over from the beginning.