Quest compass:First a little explanation, a map marker is a marked position on your map and the compass just points to a highlighted marker. The others remain inactive until highlighted.
For the quest compass it could still be present similar to how it was in Oblivion but with a few changes. Instead of directly pointing you to your goal it always points to the next goal your character KNOWS about. To explain it better, think of this:
You have to find a certain person and only know the general area where he lives but neither the town, street or house. In that case the compass will point to center of the area or the capital of that area, so you roughly know where you have to search.
Then, after asking around a bit, you might know what town/village he lives in, the compass will then point to that town but again not where EXACTLY he lives. Asking around further you might learn the street or exact address which will place a marker there.
However the person still might not be there but you can gain further info, where he works (will place a marker at his workplace as well) or where he usually eats (places another marker there). That way you can narrow down where that person MIGHT be, at times where he's usually at that place the compass will point to the corresponding marker.
However there is a possibility for the marker directly showing your destination when you exactly know where something is OR if the target is in your direct line of sight.
It's hard to recognize a person on a computer screen but your character can, when a person you seek is in your line of sight and close enough he can have a marker since your character can see him now. Similar for objects you're looking for, when they are in your line of sight they can be highlighted.
That way you could also spot a NPC or target over larger distances through a telescope for example.
So basically instead of directly pointing to your goal it simply narrows it down more the more exactly you know where you have to go. If you know the area it will point to the areas center, if you know the closer area it will point more exactly to that point and if you know exactly where it WILL point exactly there, that includes directly seeing it.
And once you pinpointed a location it will set a marker there.
You could still set a marker manually and then make the compass point towards it. That way you can manually pin a location like something you want to explore later on or already know that something is there.
There might also be the possibility to have a "faded" marker, for example when following a person the faded marker will show at the last position where you saw him or where people last saw him, if too much time passes that marker might even go away.
I also had a thought on finding objects again, once you picked up a quest object and then KNOW it is one (once you get the mission to get it) it WILL show a marker on your map even after you dropped or sold it.
Now while many will say "that's quest guiding again" hear me out. First of it does NOT set a marker until you found the object itself, it will only do so afterwards. What this does is add a safeguard so you can't accidentally give away or lose a quest item. When you look for it again the marker will remain at it's last know position, if you dropped it somewhere look near that place, if you sold it the trader will be shown.
What this is for is mostly one thing, prevent a lot of frustration. In Morrowind it happened a lot that you just out of curiosity cleared a dungeon, found a seemingly normal item and either sold it or dropped it while cleaning out your inventory. And later found out it was a important quest item and is now lost forever.
This is what the system can at least to a big part prevent, you CAN find the lost item again since you REMEMBER it.
Oh and if you dropped it in a place where you can never get it again like a lava flow, that REALLY is your own fault then
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It could still be added that a quest item can't be destroyed (dismantled, molten, broken down...), while that would be a pretty strong hint that this is a important object it's still more subtle than a bland text message telling you it is a quest item.
Also as for markers you should be able to place various different ones on your map manually, think of "google Earth" for example. Being able to chose different looking ones would be good too and really FREELY place them and maybe add a little note to it.
A few more thoughts on customizable HUD:I already mentioned that aside being able to freely place and resize HUD elements and also that you should be able to change the look of some HUD elements. I wanted to get a bit more detailed on the last one and also add that some elements could be combined.
For example, the health bar, it could be a simple bar, number, both combined, a little 3D image of your character showing his condition, a medical image like in Deus Ex or maybe even a pulse scale. Or the map could either be square or a circle map.
About combining, you could have the map and compass separate for example or dock them together to have the compass needle move around your map (similar to GTAs map). You could even dock a clock around it to have the time, that way you'd have 3 tools (map, compass and clock) in one HUD option.
As mentioned all HUD elements should also be possible to simply turn off so they don't show during regular gameplay. In fact it would be ideal if you could fully play without any HUD at all.
Health and fatigue for example can be displayed by your character panting, vision effects, movements etc.