0) I agree with Joramund that a couple of things are not balanced perfectly. I also agree with Beo that to severe counter-measures will tip the balance the other direction.
1) Potions & priest loop - issues intertwined with each other:
You have 2 things severely adding to yout priest XP and such to your priest levels:
- Before any situation where you intend to solve by fighters more than by wizards, you deplete all your mana in shield spells.
- Once your priests are somewhat capable, every time your 4 main stats drop below 230 you pause and brew Ku/Ros/Dain/Neta potions (which after some dozen times becomes an annoying procedure, so for the sake of playability I'm glad for the DM2 aura spells). BTW: What difference is there in respect to Mana potions form DM1 vs the ones from DM2?
You have 2 things inhibiting your priest advancement:
- Very often you cast priest spells not during, but before or after combat. That means you won't get the higher XP gain that occurs when doing something within a couple of seconds after being hit.
- And of course the standard exponential growing XP threshholds required for next level.
Solutions: Well, don't overreact here, since you don't want to prevent priests from advancing all in all. Limiting potion abuse however would be a good idea, killing two birds with a stone: It would take a large chunk out of the positive priest loop cake, imho exactly as much as would be sensible, and it would reenable the stats, which are virtually irrelevant in a party with decently trained priests. I suggest for one requiring water flasks. So you can stockpile potions when finding a resting place with water, but they will be a ressource not freely available all the time. Beyond that ingredients might be added (it could be necessary to hold 1 specific ingredient in the left hand in order for potions brewing to be successful). There could be 1 ingredient per spell that could believably be anywhere from a forest to a dungeon, I'd suggest different sorts of mushroom (you could use one of the many books about magic mushroom for inspiration

). There could be special mushroom that are suitable for more than 1 spell, and super-mushroom that will allow for any spell.
To not make inventory management totally get messed up by ingredients, in such a game there should be enough bags available that can hold the components, it might be even better to inlcude an additional stacking mechanism in the engine that will allow Baldur's-Gate-like stacking (even then such mushroom stacks should be compatible to being contained in a DM2-like bag).
4) Food & water limits:
Like beo I'm rather an explore-all player, so severe limits on that would kill the game for me. I found original DM absolutely ok, if you ran out of food your stamina would go down quickly, but you can still uphold yourself with stamina-potions. I don't like the RTC method, where shortly after running out of food/water the stamina goes down so fast that you cannot even proceed to some ressources by taking a step and drinking a bunch of stamina-potions, but instead you will die before even able to do the next step.
If you'd actually make water flasks / ingredients necessary for potions, I think you would kill a third bird with your single stone here, since you could not subsist the party indefeinitely anymore.
2 & 3) Ninja class and subskills:
It is well known that in original DM you did use missiles as a beginning player, but then you found out that the damage inflicted that way compared to the pain in the ass coming from recollecting missiles is just plain ineffective compared to meleeing or fireballing opponents. Next you found out the tossing large stones unto doors will level you up faster than any real ninja combat and did so just to add a little to your stats to be a good fighter.
RTC already alleviated that somewhat by increasing the damage and XP gained from actual missile combat. Still the ninja is almost just a fighter-subskill.
Solutions:
- Have the unarmed option ALWAYS avalable alongside weapon options (always have tiny fist/boot/mouth icons right beside the weapon options).
- Include a couple of powerful ninja weapons in the game. The DM1 instructions read as if this was supposed to be, but then somehow was neglected. Of course the ninja weapons should not be just fighter weapon copies bearing a different name and class. They should be ninja-like in style (classical katana, nunchaku, maybe even a shoge with reach), and they also should be ninja-like in game terms (the close relation between outlook an in-game mechanisms is one of the advantatges of DM). The diamond edge / blue steele with it's armour bypassing is one such waepon. There could be others that increase things like flanking effect (see suggestion below). I would give weapons like the diamond edge / blue steele a stronger ninja XP component, not only fighter ones, even if you are not stabbing but cleaving.
I would include a new mechnism in the engine, specifically for the ninja: Flanking. Attack success and damage increase for attacking a monster from the side, increase more when attacking from behind, and much more if the monster has never spotted the party in the first place, like when it needs to see (and does not have a worm's tremoursense), but you are moving in darkness and approaching from behind, or simply when you are invisible.
Indeed overspecific subskills like climbing or cointossing are just inhibiting the entire class they belong to, i.e. the ninja. I would broaden them in some way. For example I would include a "steal" action in the game that allows you to transfer an item from the creature's possession into your action hand (there would need to be a list of exceptions, like screamer slices and drumsticks being unstealable, maybe by some flag), and make "cointossing" and "steal" be part of a subskill "ledgerdemain" (maybe shops could be designed that can be stolen from, taverns with gambling dialogues etc..). That would make it a ninja subskill though, not a priestly one.
Instead of "climbing" (which you just don't do often in the game) I would broaden it to "skirmishing" and have XP added to it each time you successfully use movement to your adnvantage, not only when climbing or falling, but also when you flank a monster (since that means that yuu have successfull moved past its primary defenses), and as a sidenote when you kill monsters by falling unto them. Discovering illusionary walls should also add to the ninja XP.
Parting is all we know from Heaven, and all we need of hell.