OK, let's look at the "originals" and see what we can come up with.
Diablo 1
Single player
- No difficulty setting
- Walk through all the levels (no short cuts)
Not completly true - in Hellfire addon you could choose difficulty levels.
And it saved "gates" you've entered previously with that char, like the crack to Hell.
Other RLs (ADoM, Nethack) can also be quite long (10+ hrs) and you also don't get to "restart" for XP/item scumming so I don't think it is essential here either IF the game is balanced.
These games have lots of monster spawning, and methods to use them for good item gain (i.e. sacrifice, which can also be heavily scummed).
That's why I said in my first post "unless monster spawning will be implemented", but I deem this VERY outside the spirit of Diablo ("undiabloish" just doesn't sound right :P ).
Yes, you said "IF the game is balanced". Absolutely true. But a one-run Diablo game would require, IMO right now, either very early ability-gain and quick XP jumps or a massively tweaked late/end-game, either way making all the different ability-monster crosses crowded (i.e. pitting lvl1 novas against horned-demons and steel lords, neither of which happened often in Diablo, for different reasons). And the way I see it, that's too-much not what the original game was about (even if this one's still a good game).
Another thought I had, however, and I think won't ruin the original feel much and won't hamper scoring, is a much longer dungeon, maybe with a shortish, crowded end-game like in Diablo, with "pick-and-play" ordinary difficulties, with a quickly escalating game as the challenge of harder difficulties (like with DoomRL).
But I still believe mid-game/made-char restart is a main feature of Diablo, very much worth keeping (although, yeah, tweaked to prevent easy escape :P WoW's exit-interval in game-turns?).
I think your idea of testing game-restart as a training option at first's a good idea, if Kornel can handle the load :) (Keep up the good work, man! Can't stress it enough)
As for Cleavers in Hell - could make it interesting and make unlockable item abilities for massive use and/or XPlvl.
The Cleaver could then give a strength bonus proportional to your level, and after the 600th kill/30th lord kill/100,000 XP gain with it (depending on method of balancing), gain a good chance to vorpal strike ;)
That would make pre-gens the same on every difflvl, but still way better on the higher ones (30 lords on Normal come very slowly, 100,000XP hard to gain on weakened monsters), if you play right. It also wouldn't be much off Diablo spirit, with D2's sets and XPlvl requirements.
PS: this is why I mentioned my idea now - better bring these things up early, so programming can go on later with a list of ready ideas and with less sudden questions.
Also, it lets Kornel know we're still interested :)