There is an argument among purists that Build 39 captured a specific type of horror that has been lost. The stiff sprites and the "grid-like" movement made the world feel more like a classic board game. When a sprite changed from "standing" to "crawling," it was a sudden, jerky change that could startle players more than the smooth transitions of modern builds. The "uncanny valley" wasn't present; instead, it was pure abstraction, allowing the player's imagination to fill in the gore.
In Build 39? They were a tide.