I've been playing the original diablo lately and is quite pissy because I've worked so hard on leveling a sorceror, and can't go to another difficulty (immediately like, like no yippy do-da tricks). Now that it brought back the urge to go back to 'bands and work on N'Deep, I was wondering what's your progress with DiabloRL? Now I've been going through jarulf's manual, and comparing it to actual gameplay (in other words...ya know), I've manage to gather some data that might kickstart ya when you get around to "do the damn thang". Sounds pushy, but they're only notes. That's also include mod-ability ideas, possible multiplayer ideas, such and such and suchery. I've learn to write everything down even if it doesn't fit in with the project in it's current stats.
Diablo vs. Hellfire
This is a "no sh*t" comment, but layoff Hellfire content til most of the bases of diablo is finish. You may already know that Hellfire is a expansion totally outside blizzard (more like Sierra's "mod version"), but if you also coming out with Programmer Edition, it's a good idea to just weed into hellfire content and get what you need and add your own stuff.
Also note that the pace is different between the RL and the real game. DiabloRL is actually faster. So it's good to experiment how making each dungeon area 5 levels big instead of 4 levels would work.
Magic characteristics and Speed
You may be able to add more then basic spells on if you use speed to your advantage, because most spells and it's upgrade are based on speed on cast and in play. Using speed for missles for both magic and arrow can be used as an additional to-hit, on top of using movement from monsters and players as an additional AC (like the one used for doomrl). So you can see an example of chargebolts having high miss rate, and a fireball having high KA-BOOM rate. For in play spells like firewall the damage is calculated by the monster's or player's movement speed. That is, the faster, the less damage and less time over the flamewall tile.
The tricky ones to do are lighting. Now in the diablo game, lighting is treated like a stationary spell effect like firewall, so you can consider it as in play spell. You can either do one of the two things, increase the damage more then normal per spell level and use the speed to calculate damage as you would a firewall, or freeze the player on spell cast for the whole duration as it can work well with flash and inferno.
Guardian and Elemental can be summon spells like Golem spells. Elementals are crazy fast and explodes on impact (just the wall if no enemies in it's los). Guardians are there, spitting til the spell ends.
Lastly Nova Spell, it's definitly a spell that packs a punch the closer the target is to the player. Yea, like you used to draw a radius explosion(using 92 and not 360), so does damages dealt for those tiles with each bolt.
Don't forget the cast speed before the actual cast, as interuptions can play just as big a roll as the actual spell.
Mod it up
I may have posted that you could do both. Have diablo itself inaccessable to browse and edit, and have a mod folder for modded games. If you have been at phrozenkeeps and saw how .mpq files are fixed up, consist of, and stored, maybe you can find some ideas on storing most of your future data. Note that most mods aren't zipped and compressed away, so making diablo know how to read both can be essentual.
On the future of mod-ability which have to be discusses later after that feature is possible, we can make it possible not only be able to edit material, but also add scripts. It will also help to add additional functions, and/or tags for editable data (stuff not used in the game like monster auras, curses, target selections, wilderness, and dungeon locations) for others to tinkled with with their game.
Diablos
Diablo AIN'T diablo without multiplayer. But for possibilities, how would it work for online play? No dought it has to be real-time, but with the importants of speed, we could balance that with the framerate. Spells and arrows can be animated out in real-time during play, but all are faster then on the original game to closely match the single player game. Having tactics can play a huge roll in determining targets when casting, shooting, or even fighting. A quick-fire and quick-cast key are influence directly by tactics choosen. Tactics can be modified by picking target type(demon, undead, creature), hp, level, nonresistant, and distance. It helps to have multiple tactic slot to edit.
That's all I have. I hope to see DiabloRL as big a hit as DoomRL is already...
I'll shut up now.