As for tweaks, not sure if you could even do it, but adding volume to items would make the game much more difficult and realistic. How many of us are toting around three suits of armor, four bows, fifty potions, six sets of dragon bones and 20-30 books? Maybe make it more of a 'hardcore' setting.
Could just adjust item's weight so it is an overall encumbrance. Not sure if I'm a huge fan personally of doing that, though. If you can only manage to haul one suit of armor out of a dungeon, it would annoy me more than it would add anything.
I'd like to see bad guys sneaking, sniping, pick pocketing and breaking and entering.
Not sure if NPCs can gain backstab damage or not. Breaking and entering could be done with a script... there's already some of that which happens in Riften now.
I'd like to have better sensory awareness. Right now when I'm out in the wild I get precious little feedback on what's going on around me. I hear wolves baying but cannot tell from what direction. (although I'm sure a better sound setup would help this). Maybe a yellow dot on the compass to indicate "I hear something in this direction.I think the sneaky "eye" is overpowered. Unless something is running at me and I hear their breathing and footsteps, or a human says "hey, WTF?" I shouldn't know when I'm detected.I'd like to remove the quest icon from the compass. Let me set a manual location, but I shouldn't be able to know where a person is at any given moment.
Most of those are doable in some fashion (though not really where I'd be aiming for). The quest icon removal I would be surprised if there isn't a mod out already for it. I think I might have seen something in the .ini files for turning off the sneak icon as well. Or barring that, you could probably just get the file for the normal icon, and save it overtop of the sneak one.The hearing thing might be a little tougher. Though I was under the impression if you can hear a wolf howling you can probably already see the red dot on your compass. Or soon after, anyway. It might take a lot of work to add something new like that. Probably not in the list of stuff I'd be focused on again, but interesting thought.
I'd like quests and dialogues to be more interactive. "Go get me this sword from this cave I marked on your map" quests suck. Give me more options when I speak to people. Don't have them give me the whole story.
New quests, editing quests, etc, is definitely possible. Though you'd have to record your own dialogue for them and it wouldn't match the voices being used if you want it to be audio as well. It could just be text dialogue though. One thing I have had in mind since Oblivion would be a mod that takes the normal quests and changes them just enough that it makes it feel like a new game. Maybe it randomizes who gives you the quest, so you actually have to go explore to find them and can't just head straight to Person X to start up a quest with a great item. Maybe randomize some of the rewards you get, or have different versions of quests, sending you to other locations, etc. That will be a lot of work though.
Scale magic damage up or melee/archer damage back. Powerful mages are supposed to be able to make the earth shake.Fix the stacking bonus that allows you to cast spells for free. The first item can grant 25% bonus, but the second should grant 1/2 that, and the third 1/2 of that and so on.
I think magic damage is fine with the stagger perk there, but I agree about scaling back somehow the top damage. The way to get rid of the free magic would just be lower the maximum enchantment you can get with Fortify <magic skill>.
Make it so you can't chug five potions on the pause menu. "yeah, you're about to chop my head off, but wait just a second, please while I toss back a six pack of healing potions!"I agree with the others about money... Maybe have the tax collector come by once a month wherever the player owns property?
Potions I know can be done, Oscuro changed the limit in Oscuro's Oblivion Overhaul, though I will have to hunt to see what controls it, whether it's a script or an effect or what.For money, one thing that I want to avoid is just taking cash away for nothing. I'd rather have something where you want to spend the money. Maybe charge for existing services (costs you to use the smelter, the forges, alchemy tables, etc). Maybe have some of the nicer quests where it would make sense require a bribe before the person will give you the quest. Or add new upgrades for houses. Though some of that will require dealing with meshes and textures and crap I have no clue how to do. I know how to add and move items about and such, but actually making a new item and not having it look like an existing one, I have only a basic idea of how it is done, and would rather have a graphic artist do it. Maybe could recruit someone willing.Oh, here's an idea. How about a breeding farm where you could take your dog to have a litter and let you pick out one of the pups trying to get an upgraded dog? Maybe let you choose what dog to breed yours with to try to accentuate certain characteristics (health, bite strength, speed, etc)? Of course they charge a pretty penny. Could do the same thing for horses I suppose.