Here’s a potentially cool idea for a horror storie or adventure: Lovecraftian horror set on a World War I battlefield. Usually this style of horror doesn’t work when the characters are highly armed and there are lots of other people around. But the battlefields of the Western Front are probably as far removed from normality as it can possibly get. You could have creatures stalking the muddy bogs of artillery craters and barbed wire, murdering men left and right. And while there are lots of armed soldiers all around who would hear the screams and gunshots and stumble upon the corpses the next day, nobody would think anything to be out of the ordinary. The protagonist of the story would doubt his senses and wonder if he is simply going mad, and even if he told others what he saw, who would believe him? Either he went a bit mad or he is pretending to be mad to get out of the battle.
Maybe the creature is a werewolf, or it’s a group of ghouls who come crawling out of a crypt burried below a shelled cemetery that is no longer recognizable as such. It could go on for weeks or months, with only one or two man noticing that those attacks are not normal raids by the enemy. And the during artillery bombardment the bunkers would be deathtraps for all inside if a monster gets in.
I’d read something like that.