- have horse level up, make choices to add points to attributes such as stamina/carry capacity, loyalty, speed, wits/survivability, etc.
This would be lots of fun. Then as you leveled up, your horse wouldn't be left behind and start being less useful (when you can run faster than your horse there's not much point having him).
Also it would be easier to grow attached to him and be upset enough when he died to load from an earlier save. Since you put a lot of work into him.
What would also be nice would be to be able to buy gear for him, and store it in the tack shed of the stable at your house. You could buy better and better gear, and enchant it too.
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One point I have in this conversation is people complaining that they are not realistic enough, and in the same breath complaining that they can't run over rocks well enough. Duh! Horses are not supposed to be able to run over rocks at all!