I was just studying the picture of the main menu screen for Shattered Haven, and several thoughts jumped into my mind. Not to intrude on what you have planned, but just thought i would mention them out loud, just in case any of them sound workable.
1. The red light that casts everything in a blood red ominous sheen... could the actual sun have changed? Or perhaps this is some emanation of the creatures, so that when they are close you can see the light? It might make for an interesting way to tell, perhaps in a general way where the creatures are? Or perhaps the color has no connection at all with the game play mechanics.
2. The creatures themselves are probably certainly hazardous and hostile to humans, but what if they are equally hostile and hazardous to each other?
This might make for an interesting mechanic, if i not only have to worry about attracting their attention, but now its possible that if one intersects another, and the two or more creatures begin to fight each other, then, it might actually save me, or give me an exit that wasn't there before?
3. Connected to number 2 above, if the monsters are hostile to each other, then certainly there will probably be a hierarchy that comes into play, perhaps the snake necked creatures can take out the smaller red-eyed rabid squirrels or rabbits, but the larger bear/bull creature can eat the snake neck for breakfast easily, though perhaps not 4 or 5 of them at once, which means if they do travel in packs, perhaps 50% of the time, then the deformed and ominous red-eyed bears are not the top of the heap predator that they are normally, when they are confronted by anything else singly or in two's or three's.
4. Perhaps there is a spore, or mold that infects both plants and animals that slowly kills them, meaning that perhaps on any given screen level we could find a pack of snake necks that are in the final stages of infection and are just about ready to die, which means our characters have to not only avoid the monsters physical might, but also avoid contamination by staying a certain distance from the creatures as well, which may mean relying predominantly on distance traps, like trap holes, or trip wires that catch animals or survivors if we are not careful in disabling netting. It could also unfortunately mean, even if we avoid death at the hands, or claws and teeth of the snake necks, that if we are infected that we may only get a few more screens before we succumb. which may mean going back to try that level again? Or perhaps replacing our original character with one of the other family members, like mom, or the daughter or the adopted son? Or even perhaps a neighbor, or other survivor? In a way that is sort of like AVWW is now with the glyph-bearers.
5. Perhaps its not always monsters and grays that the player fights against. Maybe its the environment, maybe its a chasm that has opened up that the player has to figure a way around, or some way to get across. Perhaps by knocking down a tree? Or using a rope from one side to a tree or fixed object on the other side? Or perhaps there is a fire in the level? Which gives us only 180 seconds to get past the hazards and chasms and monsters and out of the level?
Just some thoughts. I really like the pic and the lore you have talked about. Please remember i'm not saying your game has to be like this, i'm just really musing to myself outloud about what you may have in store.
Waiting impatiently to see the beta and jump into the game.
-T