Ok, so I think we can all agree that the solution to this problem needs to fit in with the tenets of the game:
1. Game immersion. A simulation of the created world and it's boundaries (which are few)
2. Everything is interactive. You can pick things up, move them around.
3. Survival. You enter with nothing, and need to find a way to survive.
Given the above, let's look at inferences based on the premise of the game:
1. You're a commoner, you may not even know how to read. If signs exist, you probably can't read them unless reading becomes a skill, which requires a new game mechanic.
2. I would tend to agree that private structures, especially those that have been occupied by monsters for x amount of time, probably don't need signs because the original inhabitants probably learned the layout over time. It was their home. Do you have signs outside every door in your home (size matters, but I hope my point is taken)?
3. Not everyone survives the same way. Some people have the mental capacity to memorize the layout naturally. Others may be focused on finding gear so they spend more time in a room than another person. It is not for anyone here to decide how SOMEONE ELSE should survive.
So, it is clear from the posts of members that needing to understand the layout is important to survive, whether it be for remembering where you have been, or which rooms are easier to battle in, or for whatever. You start out with nothing but some clothes and your journal. Mini maps and found maps seem contrived, aimed at being a helper tool simply given to users (again, did you have blueprints of your house stashed in a drawer somewhere?). However, if that is what I start with, and I have a need to learn the layout:
1. I start exploring, hoping I find a writing utensil. If I find one, I'm gonna pick it up and use it.
2. Marking areas may occur to me, but using weapons or pieces of debris to smear blood on walls is not very effective. You are always holding sharp or blunt objects, and the walls are made of stacked stones, but the architecture is not nearly as sophisticated in the Exanima world as they are in modern society. Moving objects by doors to mark them is an option. Yes, it may be tedious, but it would be so in real life as well. Marking with soot from a torch might work, but first you would need to extinguish your torch, and be sure you have a way to reignite it. Also, that soot won't stick around forever. Maybe it's a decent short term solution. Using a piece of clothing with blood on it might work, but may be difficult to implement and many of the monsters are skeletons which clearly have no circulatory systems. Both blood and soot seem unreliable to me, because the walls are nowhere near flat, and could be dusty, which would lend to the impermanence I eluded to earlier.
3. I would continue exploring, hoping to come across a writing utensil for my journal, or maybe a brush to smear some other liquid around. Who cares if you draw dicks? You are playing a single player game, and if you need something to keep your spirits up in the face of death, then draw dicks. Who cares?
4. Let's say I find a pencil or a graphite rod. NOW I have something to write in my journal with. Drawing letters sounds like a pain with a mouse, so using the keyboard seems fair. However, for the layout, it would absolutely need to be hand drawn with the mouse, because you would draw it manually in real life. For one thing, the implementation for drawing with a mouse would be the simplest option given other possible UI solutions. Some people may be natural cartographers, and some not. This is where the player actually needs to use their mental capacity to improve their mapping skills. All of the first maps in the world were hand drawn. Some people may put a 'D' to mark a door, some may be more meticulous and draw a much more detailed map.
Those are my thoughts. I would opt for the manual map option because it still requires the player to do all of the thinking and work. You still have to find something to draw with, which lends to the realism and immersion in the game. Not only that, but drawing in your journal would be *persistent*. You draw with soot, and weeks later you realize you need to revisit a place, the soot is gone. But your journal remains with you. Your intellectual property remains yours. I do NOT think we are just trying to make the game easier here (I'm looking at you, Syllabear!). These are natural realizations of necessities to survive! We clearly all naturally came to the conclusion that reliable navigation is a necessity for survival in a large, unknown place. If some people can memorize, then they will just get through levels faster. If people are more meticulous and want to spend time drawing in the game, then that is their prerogative. It doesn't make them cheesers, nor does it make them cheaters.