Two decades later and still no 'real' way to select difficulty settings in single-player, huh?

fucking

yikes

This is how it was.... Few games offered difficulty levels, and no RPG did, because they where mostly based on Dungeon crawler. Diablo is sort of a simplified "rogue" with less items and mechanics, but cool graphics and real time action.

There are tho, some "secret" difficulty levels.

If you get warrior, it is easy, any other class is "fuck you" difficulty level. As you survive and go trough levels, you'll notice that archer is medium and wizzard is hard.

However, by the end game it would be reversed: All classes can easily beat the game, but wizzard will become the easiest, archer still medium and warrior/barbarian the hardest. The problem is surviving the first levels!

In this case it's a bug though; they added difficulty levels at a late stage in development and only implemented them in the multiplayer menu, not single player. Even if you trick the game into starting a higher difficulty single player game, the difficulty isn't saved anywhere in the savefile. So fixing it properly would break backwards compatibility and also be far out of reach of what GoG could do considering they only have the binary files, not the source code.

the trick you'd have to do it every time. or you can use Hellfire for that.

if you really want to progress a character through Nighmare/Hell and get higher levels, an easier way would be to start a new character in multiplayer mode, you can play by yourself offline via the IPX or Direct Cable option. this makes your save game like it is in a multiplayer game, so no manual save/load and if you die, items drop on the ground and you'd have to walk back to grab it. then if you'd like to play with a friend, you can still use the character, unlike singeplayer.

However the multiplayer movde does not have all the special locations or mini quests like "Halls of the dead/blind" and so on.

I'm more annoyed at the fact that the multiplayer game still doesn't include the single-player quests.

I want to play the multiplayer version (to have difficulty level and to get the "grueling low-level difficulty" coming with mob having 2x the HP compared to SP), but I'd REALLY like to have the SP full quests with whole mini-levels rather than the MP quests "just drop a boss in this level".

At the very least, I would have liked a way to port single-player characters to MP and back :-/

Well, you "sort of" can, if you can find a character editor. But that would be cheating a bit as some of the unique items that are guaranteed drops from certain bosses are not available in Multiplayer.
It still doesn't address the issue of not having a selectable difficulty level.

I usually just go to my MultiPlayer lvl 33 Character, create a new game in Hell Difficulty, as soon as i spawn in Town i then switch to SinglePlayer and create a new game. Voila! Hell Difficulty in SP. You can totally do Hell Difficulty with a lvl 1 Character, if you're that much of a masochist.