Roguelike column thumbnail ['@ Play' is a monthly column by John Harris which discusses the history, present and future of the Roguelike dungeon exploring genre. This time -- a look at the art of item design in Roguelikes.]

It has been a little while.... This column is an in-depth examination of some of the most popular items within the two most-common categories: potions and scrolls, both of which we might term "one use" items for the fact that utilizing them consumes them.

Exploring a monster-filled dungeon is not what we might consider a healthy activity. If the game were just about looking around, mapping territory, and killing monsters until the player's inevitable demise, the game might be interesting in an simplistic kind of way, but it wouldn't have that roguelike spark. No, the player must get something out of the exploration. That something is treasure.

Treasure is the carrot held in front of the player's face, leading him on into ever-more dangerous situations. The majority of treasure in most roguelikes is found laying around the dungeon. Some of the treasure is food, and the need to find more is what prevents the player from building levels indefinitely on the easier levels, but the good stuff is what pushes him downward. Unlike the trend in most RPGs these days, equipment is often a larger component of player power than experience level in roguelikes, and it is randomly generated.

The justification for treasure

Why is it so satisfying to find treasure? It cannot be denied that, without it, many roguelikes would be a lot less interesting. I suggest the reason that the expectation that players will find treasure, or other things and opportunities of value, in those dangerous places they explore is related to the exploration urge evolved out of humankind's tribal pre-history. But I digress.

The randon treasure generation is the biggest scrambling factor in a roguelike. Monsters are random, but still appear in the same proportions on each level. Dungeons are random, but even with traps most of the time the maps are not themselves very interesting. But a single item of treasure, in a good roguelike, can have the power to change the game significantly, and the variety of powers they grant, intersecting with each other and the monsters and dungeons, is what allows different plays of a single roguelike to seem different from each other.

The biggest problem with giving players lots of treasure to find is in determining how powerful it should be. If it's not powerful enough players may consider, why bother? If it's too powerful then it's unbalancing, and it is more the treasure that is the reason for success than the the player's skill. It might be useful to examine the basis for treasure in the source from which RPGs arose: fantasy literature. Bilbo's ring, for instance, enables him to overcome many of the dangers in the latter half of The Hobbit. Setting aside the ultimate identity of that ring revealed in The Lord of the Rings, a lot of the characters in that book kind of equate the ring's powers with Bilbo himself. They say that there is something more to him than meets the eye. That thing is, literally, the ring. But he found the ring through his own wit and guile, so it does make a kind of sense to say that. And even with the ring, Bilbo is in danger and must use it wisely to escape from dungeons, dragons and wars. In other words, Bilbo's possession of the ring is a manifestation of his ingenuity. So the treasure found in a roguelike, since it is gained by the player's own wit and guile, is a manifestation of it, and it is the job of the designer, as creator and custodian of that world, to have it be fitting.

We've already given an overview of the primary types of roguelike treasure in a general article some time back. It is interesting that, although Rogue is over twenty years old now, the major item types provided by that game remain the major types used in nearly all roguelikes. This is the first of a number of columns that examines the primary types in detail. In this first column, we look at one-use items, which are used a single time and are then gone.

Disposable Magic: One-Use Items

The primary one-use item types, other than food (usually a simple case) are potions and scrolls. Some games also provide for random food items like berries and mushrooms. Shiren provides herbs, which are good for a small amount of food value when eaten, but generally function more like potions. This can be seen in the way that a good number of herbs provide special effects when thrown. ADOM has herbs which are unique in that their functions are not randomly scrambled, but are the same from game to game. (ADOM's herbs have other unique and interesting properties however. They are one of my favorite things about that game, but they are a special case that doesn't fit in with the general roguelike categories.)

Scrambled one-use items are among the more difficult to identify items in a standard roguelike. The biggest problem with identifying one-use items is that, once the item is gone, it isn't there anymore. You only get once use with which to discover its purpose. And a few of these items are situationally useful, to the degree that the player may be helped considerably by using the item effectively, at the proper time or with specific preparation. And a few one-use items can cause a great deal of trouble; Rogue's potion of blindness can be a game-ender if used at an inopportune moment.

Many games auto-ID potions and scrolls upon use, but Rogue and the Hacks do not. These games require that the item's visible effect be detectable by the player, and are obviously the purpose of the item, before they'll auto-identify. Some items have effects that are so obscure that they never auto-ID this way, forcing the player to either name it themselves from experience or expend an Identify scroll on it. Others only identify sometimes (like detection scrolls when there is something to detect), and some will prompt the player for a temporary name in some situations.

The one-use-only property of potions is one area where roguelikes differ from classic Dungeons & Dragons. By-the-book OD&D and 1st edition AD&D state that found magic items are unknown, but potions may be tasted and thus given a chance of identification without consuming the thing. In those games some potions have multiple uses, and others have functions that require the liquid not be drunk at all, but instead applied to an object or the skin, or in some cases the bottle merely unstoppered. The classic roguelike play style is directly inspired by these versions of D&D, and both Rogue and the Hack-like games provide for item uses beyond the basic "quaff." In Rogue and Nethack throwing potions at monsters is an option for getting effective use even out of "bad" items. In Rogue, this may cause the item to affect the monster; in Nethack, a thrown potion breaks and may subject nearly creatures to a reduced "vapor effect." Nethack also allows for dipping items into potions, and even mixing them together, each option of some strategic worth. Both games, also, contain Scrolls of Scare Monster, which are wasted when read. Their true value appears only while they're resting on the floor. But even so, most potions are still meant to be drank.

potion.pngThere are usually many one-use items to discover in the game, and unlike random wearables (such as rings and amulets) the player usually will get a fairly substantial hint for what it does upon use, so, scrolls of identify are generally best used for other things. Significantly, identify scrolls themselves are random one-use items in most games. In many games, before any items can be identified by using them, the player must trial-and-error to discover them. Games that support selling items to shops often provide identification hints by offering items to shopkeepers, a tactic I refer to as "price ID." The usefulness of this strategy ranges from slightly unbalanced in Nethack to nearly essential in Shiren's Final Puzzle dungeon. Because this trick provides one of the few ways to narrow down object functions that doesn't use the thing up or require knowledge of Identify scrolls, it is particularly useful when applied to one-use items.

What is the functional difference between the two classes?

  • Potions are much more likely to have an effect when thrown. The only roguelike (or roguelike series) I know that provides thrown item effects for scrolls is Shiren the Wanderer.
  • Potions are, basically, chemicals, and this avenues for useful non-magical potions are much greater than scrolls. For some games this is a significant difference: should a potion of magic detection locate a flask of oil? In Nethack, the most useful and potion is water. It is similarly useful in ADOM.
  • Potions may also be more versatile in their uses than scrolls. In addition to being thrown, it may be possible to dip items into them, or to mix then together. Nethack uses hard-coded potion mix results according to type. The Color Alchemy patch randomizes potion results, making them mix according to potion color and subtractive color mixing. ADOM puts a lot of work into its alchemy system, defining a number of mixture "recipes" randomly at the start of the game, and granting the player knowledge of them as he advances in the Alchemy skill.
  • While scrolls may have many varied effects, potions usually work on the subject's physical form. Note, however, that this is not always the case; some detection effects may be implemented as scrolls, and others potions, in the same game. (D&D did this too sometimes; there is a line of potions for controlling various types of creatures. These potions work by the user drinking them; their influence then extends outward from the drinker, apparently.)
  • If the effect requires any further input from the player, particularly selecting an item to work on, the item will almost certainly be a scroll.

Here's a list of some of the most notable items in the class, from various games, and their interesting properties.

Potions

... of Healing (and Extra/Full Healing, Cure Light/Moderate/Serious Wounds, and so on)

Other than weapons, potions of healing may be the most common item among all roguelike games. While most roguelike characters heal quickly (usually returning to maximum hit points after at most a hundred turns of rest), the danger presented from facing multiple opponents at once, or surviving an encounter with a single powerful monster, sometimes necessitates a way to restore hits rapidly.

One of the most interesting gameplay choices in these games is the traditional max-HP-boosting trick of healing potions. If you drink one when you're at full health, many games will let the player push against the ceiling, giving him a tiny, permanent maximum HP increase. This seems like the better use of these potions at first, since the main method of gaining maximum hits in most games is gaining an experience level and those are rather harder to achieve, but the best move depends on your situation. Weaker healing potions are probably best quaffed for max health, especially later in the game, but the stronger ones can be so effective that they may come in handy when escaping from a superior foe, which the restrictive vision rules of Rogue make essential. Another obscure use of these potions is to instantly alleviate status effects like confusion and poisoning. Stronger types generally cure more types of these ailments. This use is of great importance in Nethack when facing certain rare, but very dangerous, Demogorgons situations.

One thing about healing potions is that giving the player an abundance of them can be less damaging to the design than you'd think. They require a turn to use, and a foe that really outclasses the player will probably put him right into trouble again with the next hit. Shiren the Wanderer has an item, the Chiropractic Jar, that instantly heals the player completely and restores most status ailments. These items have multiple charges and are not usually rare, and yet the game still has a reputation for lethality. This happens because the player must have both time to use the item, and the presence of mind to use it, and also because for their commonness they are still a limited resource, so the player tries to conserve uses. This often proves to be deadly.

... of Restore Ability
The only one of D&D's six attributes to make it into Rogue is strength, which influences bonus damage done to monsters. The game begins players with a score of 16, and it also tracks "maximum strength," which also starts at 16. There are monsters, traps and items in the game that can lower strength. All of these effects leave maximum strength alone. But unlike hit points, strength does not regenerate naturally over time. In Rogue, only the potion of restore ability, which resets strength to its maximum score, can undo damage done to it.

Like the danger of losing armor value, the danger of strength loss is mostly specific to a limited region of the dungeon, that which plays host to rattlesnakes, which by far cause most of its attribute damage. One consequence of Rogue's sight rules (only one space around the player is visible in corridors and dark rooms) is that there are certain times when it is impossible to avoid taking a hit from a monster, which means sometimes strength loss is unavoidable. This makes restore ability potions fairly important.

When I say "maximum" strength, what I mean is the player's current maximum capacity for it, which is considered to be its value when all attribute damage has been restored. Most other roguelikes provide more stats, with different functions, but they usually expand Rogue's ability restoration potions to work on all of them.


map.png... of Gain Strength (and other stats, and Ability)
In Rogue, a potion of gain strength increases the player's strength score by one. If it was already equal to maximum, then both strength and maximum strength increase by a point. If the player has taken some strength damage though, then the result is that only one point is restored.

This means, if strength is later lowered, that drinking a restore ability potion will return strength to the new maximum. Having high strength is a subtle, yet significant, advantage, so it's fairly important to save these for when the player is at max strength.

The trick to these two items lies in the inescapably of strength loss. Most characters will take at least a point of strength damage during the game, and often more. Both types of potions are generated randomly; it is possible that none of one type will appear in the game. If your strength starts getting dangerously low and you haven't found a restore ability potion yet, is it a good idea to increase your damage done by one point by drinking a gain strength potion, or is it better to continue waiting, hoping to find a restorer to drink first? Keep in mind that the player doesn't even know which potion is which at first, and often one potion type, poison, will drain strength. At their best, roguelike games are full of these kinds of choices.

ADOM has probably the best-developed statistic system of the major roguelikes. Whereas most games satisfy themselves with, or something like, D&D's six stat system, ADOM has nine, and provides individual potions for improving all of them... and potions for temporarily boosting them, and potions solely for raising their maximum. (It also has the diabolical Potion of Exchange, that swaps them around. This can easily ruin your game if drank carelessly.) Additionally it has potions of Gain Attributes, which are more general but do not raise maximums. Of particularly awesome note: ADOM's system has no hard limit on how high stats can rise, although it becomes much tougher to increase them as they go up. Interested readers are directed to the Stats chapter of the ADOM Guidebook.


... of Gain Level
Another example of a difficult choice is deciding just when to drink a potion of gain level.

As is normal for role-playing games, each experience level requires a rapidly-increasing number of experience points to earn in order to achieve it. Some games, following from old-school D&D, even use a doubling progression. Harder monsters are worth more experience points, it is true, but in many roguelikes they don't quite keep pace with the higher point totals needed, meaning levels games come more and more slowly. Rogue, particularly, is infamous for monsters that generally get harder faster than the player gains ability. Rogue characters thus get put into ever increasing amounts of danger as they delve down, and every experience level counts.

As a consequence, the longer the player waits before drinking a potion of gain level, the more value he'll get from it. If it's used early, the experience points gained will be dwarfed by the amount received for killing even one monster. On the other hand, the longer you wait the less the portion of the game you'll have made use of it, and if you get killed the advantage is lost.


... of Poison (and Sickness)
This is an example of a bad item, one that has no good primary purpose. Nearly all roguelike items have a good secondary purpose; bad potions can be thrown at enemies for example. Even the worst item can be useful if a nymph happens to steal it instead of something better. But the "usual" method of using potions, drinking them, will cause you grief if you try it with poison.

Take note, poison is not, in itself, fatal. That is a no-no in games where the player is expected to identify things through use. If the player must rely on using unknown things, then none of those things can be immediately deadly! This doesn't mean using the item cannot be deadly if the player's state is bad (low on strength when drinking a potion of poison), or if used in a non-standard way (zapping one's self with a wand of death), or if a member of a very limited class of items (wearing Nethack's amulet of strangulation, and even that can often be survived if the player prays.) Items also cannot make the game as good as lost. Rogue's worst one-use item is the Potion of Blindness, a long-lasting potion that removes even the game's slight one-space vision range, but it does wear off after a few hundred turns at most.


... of (something) Detection
While not obviously useful to new players, detection means are potentially one of the most useful objects in roguelikes. Monster detection allows you to choose your fights, item detection enables you to direct your exploration, and map detection points out useful escape routes. Note that detection items are in a gray area between potions and scrolls; different games allocate this power to these classes differently. Rogue has types of both! Food detection is a scroll, while magic and monster detection are potions.


... of Confusion, Blindness, Paralysis
These items are bad when drank, but sometimes good if thrown at monsters. Saying "bad" is relative to the situation; in Rogue, a potion of blindness can be useful when entering the Medusa floors.

They primarily exist as an identification foil, to add danger to identifying things by use and to make random potion drinking in moments of danger an inviable strategy. One-use items are fairly easy to identify


... of Thirst Quenching (and Water, Holy Water and Unholy Water)
Each of Rogue's item classes has a do-nothing item, to throw off people who think all items must have some function. For scrolls it's blank paper, and for potions it's thirst quenching. The others are the wand of nothing and the ring of adornment. It is notable that Nethack still has all of these items, but with special uses for three of them.


Scrolls

... of Identify

The scroll of identify is, after healing, the most common of roguelike items. In many games they are also the most-often generated item.

Here is something I find very interesting. Scrolls of Identify are very common, but I am aware of no roguelike game that will purposely misidentify something. Nethack's cursed scrolls of Identify identify fewer items, not lie to the player about what things are. D&D has dangerous objects that purposely resemble useful things, and the diabolical potion of delusion that, depending on a group's play style, could cause the DM to lie to the player about what is happening to his character. Roguelike games, while tricky in the knowledge games they play, do not tend to go that far.


... of Enchant Weapon/Armor
These items are the scroll versions of the potion of Gain Strength. That potion increases the player's damage-dealing abillity by increasing his physical attack bonus. The scrolls increase weapon attack bonus and decrease enemy hitting chances, while the player is using a specific piece of equipment.

All of these items improve the player's state indefinitely. They do not expire naturally, but must be undone by enemy attack, unfortunate item use, or trap. That makes these items extremely useful. Although a single point of bonus is a rather subtle effect in a single encounter, over time the benefits are profound. If the player is lucky enough to find several of these the game will become much easier, maybe even too easy. Most games guard against this possibility by limiting how high strength can be raised, or how far an item can be enchanted. It is kind of a cheap way around the problem, since it means a whole class of item suddenly becomes useless just because the game designer thinks the player is getting too powerful, but it is frequently used.

A particular note... in Rogue, scrolls of Enchant Weapon are unusual in that they increase one of a weapons two pluses. That game distinguishes between pluses to-hit and to-damage, and the scroll decides randomly which of the two values is increased. Some Rogue variants split Enchant Weapon into two separate items. And some go the other way, and combine the Weapon and Armor scrolls into a single "Enchantment" scroll, which asks the player which item will be subject to the item's power upon reading.

In most roguelikes, these scrolls function immediately on a relevant item in use at the time. If no weapon or armor is in use, the scroll's effect is wasted. Nethack uses this as the basis of a subtle trap; one of its bad scrolls is that of Destroy Armor. If you're reading unknown scrolls, you might want to wear armor in order to take advantage of an unknown Enchant Armor scroll. But what if that scroll should be Destroy Armor instead? Another possible trap, used by other games, is the scroll that asks you for an item to operate on, but that doesn't tell you what for.

As an extra ability, these scrolls also lift curses from the item they operate on.


... of Vorpalize Weapon
What does it mean, to "vorpalize" something? No matter what one might have gleaned from its use in video gaming, vorpal is actually a nonsense word. It can be traced back to Lewis Carroll's Jabberwocky, where it is applied to a sword and can be assumed by context to mean powerful. Role-playing games have adopted it. although there is no consensus about what it should mean.

Rogue contains a scroll called Vorpalize Weapon. When read, it makes the player's weapon flash violently for a moment. It applies a pretty good enchantment to the weapon, and additionally chooses one of the monsters in the game to be the weapon's target foe. The next monster the player attacks of that type will die instantly. There is a drawback however. If the player tries to use a second Vorpalize Weapon scroll on the same weapon, it is destroyed!

The ideas here is to punish the player for being too greedy. Of course, the player doesn't know how greedy is too greedy until he loses his weapon. In practice, this becomes another of those little things players must learn as they play, another fact that must be acquired in order to eventually win. If this seems rather a harsh way of teaching the lesson... well, Rogue really isn't that long a game.

Nethack will destroy a weapon or a piece of armor if it is over-enchanted. When a weapon is enchanted beyond its safe limit, it vibrates warningly. A further enchantment has a very high (but not for certain) chance of destroying the weapon.


... of Confuse Monster
To a new player, this is one of the more enigmatic items in Rogue. Upon reading the only immediate effect is that the player's hands begin to glow red. This causes the next monster the player strikes to become confused for a short while. That is all. In principle this is a powerful item, although reading it in advance of combat usually creates a risk of it being wasted on a weak monster.


... of Scare Monster
One of the most mysterious items in the game if the player doesn't know its secret. It is also the only one that can be identified without picking it up. In fact, especially in Rogue, it is best not to pick it up until you've gotten at least some use out of it.


... of Genocide
The scroll of Genocide, often thought of as a Hack item, got its start in one of the later versions of Rogue. When read, it wipes out one entire type of monster from the game.

Items that powerful, in a good roguelike, will have a tradeoff, and in Rogue it is that other types of monsters become more common, to fill the generation hole left by the eliminated species. Plus, according to the Rogue Vede-Mecum at least, there is only one of these generated in a game, preventing the player from wiping out too many monsters.


... of Maintain Armor
This scroll, which prevents armor pluses from being reduced, is one of the most useful items in the game. Seriously, it is almost overpowered! It is a late addition to Rogue's item list, appearing in V5, and it is one of the rarest items. There is a good reason that many later roguelikes do not include it.

Armor can be harmed both from enemy attack (by Rust Monsters or Aquators, depending on the version of Rogue) and from traps. One of the many little devious facts about Rogue is that even permanent advantages can usually be undone due to unwise play, or even bad luck. Getting your strength up can be undone from a single unlucky encounter with a Rattlesnake, for example. The balance between the possibility of the player getting super strong armor, from finding a suit of plate mail and a number of Enchant Armor scrolls, is that Aquators will easily weaken armor, and rust traps become progressively more common in the deeper dungeon.

These armor ruiners can be overcome by working on building an emergency set of armor (which is balanced due to the fact that it costs two turns to switch to it, and the possibility of putting in cursed armor which cannot be removed easily), by using unrustable leather armor (balanced by its being the weakest in the game), putting on a ring of Maintain Armor (balanced by increased food consumption), and reading a scroll of Maintain Armor, which... has no drawbacks.

It has no drawbacks! Except perhaps due to it only affecting a single suit, which is nowhere near as bad a drawback as the other things. If you put this on plate mail, you have just made one of the few unequivicably good decisions you can make in Rogue.

Nethack's analogue for this is reading a scroll of Enchant Armor while confused, which provides rustproofing, and is similarly powerful (although possible to remove in rare cases). Shiren has Plating scrolls, the effect of which can be removed by a certain monster (which nearly never happens). Both are, in my opinion, subtle failures of design.

Thanks to Keith Burgun for the artwork!