It's tough to say how exactly the horror theme could be emphasized here (outside of the general atmosphere from the art and audio, which already support this quite well), especially since the gameplay revolves around strategically killing the game's creatures somewhat frequently, which somewhat decreases the creatures' intimidation factor (which is something that I wouldn't want to suggest tampering with too much, because this gameplay also provides a decent amount of potential for mechanical depth, especially when multiple creatures could potentially be dealt with at once through strategically firing bullets and timing the rewind correctly). A few ideas come to mind for how to balance mechanical depth and atmospheric tension (though keep in mind I'm speaking purely from speculation, not experience, and so I could very well be wrong). Perhaps the player could be further incentivized to avoid getting noticed by the creatures (and potentially even hiding from the creatures if the need arose?), which could perhaps strengthen both strategy and creature intimidation. Uncertainty/tension could also be increased through potentially creating different types of creatures or through finding ways to further emphasize the dark. Though, again, this is just speculation. The current gameplay is very solid, and so I mainly only recommend these ideas if you wish to emphasize horror in this game.