Here is a question: What rules do you follow when playing these games? These can be either cheating you allow (like hex editing your save for max HP) or self imposed restrictions. (Remember to state the game you apply the rule to.)

Here are some I am thinking of applying to my next Dungeon Hack playthrough:

After gaining a mage level, you may hex edit your save to learn one spell of your choice, provided the spell is of a level you can cast. (Data starts shortly after $6F0, with FF meaning you don't know the spell, and any other is the number you have set to memorize.)

Vampiric Touch may not be used if your life bar is blue. (This rule is there because otherwise you can accumulate hundreds of "temporary" hit points.)

Some other rules you might consider:

Single class mages may hack one or two extra spells of up to 3rd level at the start of the game. (This rule is there to compensate for the spell picks (from the above rule) they miss due to starting at a higher level.)

Triple class mages may hack Improved Identify at the start of the game (change $70A from FF to 00).

On reaching a new dungeon level, you may hack your Maximum HP to the maximum possible. (Alternatively, apply this rule when gaining Constitution or only when reaching the level at which you no longer get to roll for HP at level up.)

If Death Real is enabled, you may not reload saves. You may only save when you quit, and may only load that save once. (This rule turns Death Real into true permadeath.)

That is something that I never quite understood. In later AD&D games a mage can pick a new spell at level up. How is that supposed to work? He levels up and gains knowledge of a new spell through divine intuition? I mean it is useful for character progression from a mechanical point of view, but RP wise?

I like the older model more, where a mage must gain knowledge of a spell separately from accumulation enough xp to being able to cast it. One could stumle across a scroll (which btw should not vanish after transcribing it into your spellbook) in a library or buy it in a shop or be taught by another mage. Makes more sense to me.

I would think it is assumed that the mage has studied higher level spells before but was never able to fully understand or master them, or maybe the mage is carrying spellbooks that contain these spells but the mage can't fully grasp how they work yet, and when a new level is gained it's like a higher level of understanding - suddenly it all makes sense to the mage. IIRC, in those CRPGs the mage gets a basic choice of new spells on leveling up (which could be those contained in the average spellbook a mage would carry around), but by scribing spells from other sources, a mage can also learn some that aren't in the basic book of 101 of spellcasting?

As to the OP's questions, I don't follow any strict rules when playing games. I usually play on Normal difficulty and try to go along with the rules of game, but if I discover exploits I'm not above profitting from them, if I like them. I wouldn't click on the same NPC a hundred times to get gold or xp from him, because the devs forgot to set the "Do only once" flag, but I would take advantage of a flawed AI. If the game allows maxing out important stats, I'd do that too, because most of the time there is no advantage to having weaker stats. I can understand giving yourself a handicap in an action game based on player skill, if that makes the game more challenging, but I can't see what's so exciting about failing your dice throws round after round after round. That's just boring. I'm not interested in cheats, unless I get hopelessly stuck, bored or frustrated, but when that happens I don't have a problem with them. I care more for my own enjoyment of the game than for comparing my 'honest' achievements with other players.

RP-wise, the mage is studying during downtime.

The old model is a bad model, because it relies on referee fiat / pity for your character's primary abilities. I actually agree that finding spells in computer games is more fun, but that's because computer games are primarily singleplayer and operate on a different dynamic.

Tabletop games on the other hand are group activities. As a group, you have more important goals, and your character should be pulling their weight at all times. As such, they are required to have level-appropriate abilities, so acquiring new, better spells when you go up a corresponding level is mandatory. Players should not be forced to jump through hoops and negotiate their characters' mandatory abilities, and a group of four cannot afford to waste screentime and derail plot threads levelling up each character.

There are a few issues even in single player computer games:
1. The developers may decide not to place a certain low level spell early in the game, making the spell useless by the time you get it.
2. In games where loot is random (Dungeon Hack), you might never get certain spells. This can get frustrating, especially if the spell is fun to use. (For instance, in my current playthrough, I have not been getting many damage spells. I only recently got Fireball, and I still lack Lightning Bolt or any mage attack spells above 3rd level, and I am already able to cast spells of the highest level available in the game.)

Of course, it has always puzzled me how AD&D cRPGs have used scrolls for learning spells when the P&P rules emphasize learning spells from other spellbooks.

Especially in the old days, it was easier to program in a single spell. It also makes it easier to control what spells the party has when designing areas and monsters.

It is true that AD&D was a pen-and-paper game and the CRPGs are single-player computer games.

I always figured the mage went to a higher-level mage to be taught, where he'd naturally pick up a spell.

What would he be studying, that would give him access to a new spell? He is in the sewers with his party and carries his spellbook. How is he going to learn a new spell by looking at his old ones? He needs input in form of a tome, a bundle of scrolls or another mage and that should be shown in the game.

I understand you coming from a power gaming point of view, though.

I have thought of some others:

For mage multi-classes:
No wearing armor that prevents spell casting

For thief multi-classes:
No wearing armor that interferes with thief skills (I'm not sure how that works in this game)

Other ideas:
Limit n spells in effect at once (try n=3 maybe?)
Forbid Create Food/Water and Heroes' Feast (make food meaningful)
Forbid Improved Identify, except on weapons
Forbid True Seeing (especially in dungeons with illusions)

Practice, the same as every other class. How did I learn Java by looking at source code? How did I learn to position a backpack to not wreck my back? The mage knows fireball is a spell that exists, and he also knows how to cast Magic Missile, Burning Hands, and Flaming Sphere.

D&D's society is a pre-industrial society. If you want to play Logistics and Dragons, you can play Logistics and Dragons, but it will destroy any published setting within weeks. what
.
. I assume basic developer competence. In a videogame, the adventure creator is the developer, and it's their task to place level-appropriate loot. In a tabletop game, the rulebook writer is the developer, and the GM is yet another player. So while a singleplayer videogame can have a mundane fighter who completes challenges by finding appropriate pre-placed equipment, a tabletop game needs to have magic item availability enshrined in the rules.

In Dungeon Hack, you're not supposed to get the full complement of spells. Empty levels are bad, though; they should have programmatically ensured that a mage can find at least one spell per spell level, much like they've ensured that a magic weapon is generated before monsters immune to mundane weapons appear.

But you had java source code to look at. Try learning java by looking at turbo pascal source code.

Characters keeping competitive without external input.

The thing is that sometimes the game might not let you play tour character the way you want. For example, in my current playthrough, my character has a lack of arcane damage spells. Fireball and Melf's Acid Arrow were only learned recently (after getting access to 7th level spells) and my character has no higher level spells of this sort other than Otiluke's Freezing Sphere, which I believe is not that good for its level.

(It's also worth noting that one spell per character level is not enough to learn every spell, though it may well be enough to learn all the good spells.)

I mean one spell per spell level, specifically in Dungeon Hack. It's a pseudo-roguelike, it doesn't allow you to play the character you want by design. I mean, I'd love to get crowned with Vanquisher on the first level of the Village Dungeon, but it's not going to happen, and that's okay.

The problem is that sometimes you don't get a spell until it's no longer useful.

Maybe I want to play around with aspects of the game I missed the first time around? Maybe I want to try relying on attack spells instead of melee, but the game isn't giving me enough? Maybe I'm tired of relying on Spiritual Hammers (which you get reliably)? Maybe I actually want Armor and Shield to be useful?

Also, I think the idea behind Dungeon Hack is to play the game the way *you* want to. Why else would the game allow complete control of your character at character creation and allow you to create Custom difficulties? (I still think there should've been an option to disable enemies with instant-death attacks, however.)

Here are some possible ideas for the Gold Box games:

1. It is permissible to hack a female character's strength up to the male character's strength limit. (Altenatively, it is permissible to create a character as male and hack the character to female.)

2. It is permissible to hack a character's race to human, train, and then hack the character's race back. (This rule allows you to bypass demihuman level limits, a mechanic that many people don't like.)

3. It is permissible to hack a single class demihuman character's race to human, dual class, and then hack the race back.

4 (a bit more of a stretch). It is permissible to create a character in one race and hack the character to another, provided the character's stats are legal for the new race. (This rule would allow Dwarven Cleric/Mages, for example.)

Incidentally, in Dungeon Hack, you could hack a multiclass character's race to Human and use a multiclassed Human (not normally possible), but I think the level limits work for multiclass characters in that game (but not single-class characters).

Side note: If you allow 3 but not 2, which demihuman dual classes work best? (I could see X/thief working well in Pools of Darkness, for example.)