Mounted combat!! Adding horses to Oblivion was great, but having to dismount for every rat or bandit in order to fight it was a little dissapointing.
Also, less levelled lists please. Make creatures/bandits/etc cap at a certain level so we won't have bandits in full daedric armor at level 20. The same applies to levelled rewards and artifacts. I don't want to find the level 5 Mentor's Ring; I want the Mentor's Ring. To me, adding 5-10-15-20 versions of legendary artifacts was very dissapointing. It almost felt like a MMORPG where everything needs to be balanded. For a singleplayer game it doesn't matter if the player can obtain an artifact at level 1; but it matters to the player that he can jump in joy and feeling powerful for finding a legendary artifact in an ancient crypt/dungeon.
Which brings me to dungeons in general. Please do away with the seemingly 'random generated dungeon #15 with random levelled loot in loot chest #3'. Please make dungeons/ruins feel unique and add in unique items so the player actually wants to explore. To me, finding random levelled loot in every dungeon took a lot of fun away from the game.
More diverse use of magicka and alchemy systems (as we had in Morrowind); not the 'this is your soul, this is what you get'. I want to experiment, add effects, combine effects, fiddle around with it for hours until I find that one combination for my Daedric Battleaxe that is just perfect
More equipment slots for customization of your character.
No staff-cannons. Every staff found in the game felt like it was some kind of gun. Add the staff back as a skill, so mages can wield it (and enchant it) with pride
Less mainstreaming for the casual gamer as even they are not completely braindead. These games are supposed to teach us things and make us think and learn. You can't learn when a magical compass just tells you that the evil lord Olibaka is currently walking around in the second level of this dungeon you never been to. Putting the dungeon on your map ('Here, let me show you the location on your map') was cool and immersive; holding your hand until you come face to face with your objective was not
A vast world needs a deep history. Morrowind had this feeling of actually being part of it. Oblivion felt kinda artificial. The world needs a soul
No psychic guards that pursue me no matter where I are and treat me like dirt for accidentally picking up a spoon or killing someone in a dark alley. No witnesses = no consequence. Minor crime = 'excuse me %20playername, but we have a report of you stealing a spoon from %20npcname' -> player - 'I'm sorry, it was an accident; here is the spoon'
Special encounters warrant special treatment. Instead of using an invisible troll for the Uderfrykte Matron or a whining Altmer for Mannimarco; make such encounters more memorable.
More skills, not less. Even though I rarely used Medium Armor or Spears; it simply adds to the richness of the world in being able to choose them anyway.
More voiceactors for the different races. I don't want every Nord/Orc or Bosmer/Dunmer/Altmer to use the same voiceactor. I want my Dunmer males sounding like gravel etc.
Seasonal changes. To me this process can simply be done by a form of disable/enable. This would put a different texture on the leaves of trees depending on the season (or fully disable them during winter to have bare trees); or packs of snow on rooftops.
Guess that covers the basics for me; and there was more but my mind cannot put them into words right now
Greetz,
Milt