Having been playing Morrowind for what seems like forever, I've gotten to a point where the game consistently ends up being too easy too quickly. I always have the difficulty slider maxed, but it appears to matter little. Thus, I'm attempting to come up with some rules to make the game stay challenging for as long as possible. Note that these rules are intended for a game with zero mods installed. The following three rules cover what I consider to be the most glaring issues with trivializing the game.
* No trainers - It's far too easy to make money in Morrowind, and the only long-term use of that is for training. Within two hours of starting a new game you can be running around as a level 30, destroying all in your path.
* No intelligence potion stacking - Creating lots of potions is okay. Creating lots of intelligence potions that in turn cause your other potions to transform you into a god is not.
* No enchanting of gear - Grand soul gems allow one to make weapons and armor that are far, far more powerful than anything in the game by default. Soul gems are only allowed to be used to recharge items.
Suggestions for other reasonable ways to limit myself would be GREATLY appreciated. Currently I'm also planning on not playing as a Breton, because the racial ability is absurdly powerful. None of the birthsigns seem to be too overdone, but input on that front would be welcome.
I don't think you have to stay away from trainers entirely. If you limit your funding, you make the game significantly more difficult. Training to the highest levels costs tens of thousands of Septims. Reduce the money the Drunken Mudcrab and Scamp Creeper have on hand, and you change the game for the better. When you're selling Daedric weapons for 1300 instead of 5000 or 10,000, you have significantly slowed you upward ascent to indestructibility.
Another idea: Don't steal anything not required for a quest. You'll have to make money the hard way, taking it from smugglers and the like.
You can modify some of the tougher creatures (Golden Saints, Ogrim, Dremora, etc.) so they are so tough, you will want to run away at lower levels (like under 30).
Modifying some of the NPCs you have to fight would be a great idea, too. Some of them have game-changing quantities of loot. Make them tougher, or remove some of the loot.
Agreed Morrowind's Achilles heal is its economy related to training. That's why you can only train five times per level in Oblivion.
If someone wanted to make the Kick-Ass Mod of All Time, it would be one that limits the number of times you can train per level to five, just like Oblivion.